Order:	Anguilliformes
Family:	Anguillidae
Genus and species:	Anguilla anguilla

William Yarrell (1836) in "A History of British Fishes":

William Yarrell (1836) distinuishes three different species of fresh-water Eels
living in Great Brittain, the Sharp-nosed Eel, the Broad-nosed Eel and the Snig:

THE SHARP-NOSED EEL.

Anguilla	acutirostris	Sharp-nosed	eel,	Yarrell, Proceed. Zool. Soc. 1831, pp. 133 and 159. Zool. Journ. vol. iv. p. 469.
"	omnium autorum,	Willughby, p. 109, G. 5.
"	acutirostris	Sharp-nosed	Eel,	Jenyns, Man. Brit. Vert. p. 474, sp. 163.
Muræna	anguilla	L' Anguille,	Linnæus. Bloch, pt. iii. pl. 73.
"	"	Common	Eel,	Penn. Brit. Zool. vol. iii. p. 191.
Anguilla	vulgaris	"	"	Flem. Brit. An. p. 199, sp. 109.
"	"	Long-bec	Cuvier, Règne An. t. ii. p. 349.
"	"	Common	Eel,	Bowdich, Brit. Fr. Wat. Fish. No. 7.

Generic Characters. - Body cylindrical, elongated, covered with a thick and smooth skin ; the scales very small ; lubricated with copious mucous secretion; mouth with a row of teeth in each jaw, and a few on the anterior part of the vomer ; pectoral fins close to a small branchial aperture ; no ventral fins ; dorsal fin, anal fin, and caudal fin united.
Baron Cuvier, in this family of the Murænidæ, or Eelshaped Fishes, which includes several genera forming his fourth order, has brought together those fishes with soft fins which have an elongated form of body: they are also destitute of ventral fins, and are in consequence called Apodal. The genus Anguilla, including our commin Eels, is the first of this order.
The general appearance of the Eel is so well known, and so unlike that of most other fishes, as to require but a slight description ; yet it was not till a period of very modern date that naturalists became acquainted with the fact that the fresh waters of several countries produce three or four distinct species which had previously been confounded together. Thus the first edition of the Règne Animal, published in 1817, included but one species of common fresh-water Eel as well known: the second edition, published in 1829, contains a short notice of four different species ; three of which, if not all four, are found in this country.
The form of the Eel, resembling that of the serpent, has long excited a prejudice against it, which exists in some countries even to the present time; and its similarity to snakes has even been repeated by those, who, from the advantages of education, and their acquirements in natural history, might have been supposed capable of drawing more accurate conclusions. There is but little similarity in the snake and the Eel except in the external form of the body : the important internal organs of the two animals, and the character of the skeleton, are most decidedly different.
Eels are in reality a valuable description of fish : their flesh is excellent as food ; they are very numerous, very prolific, and are found in almost every part of the world. The various species are hardy, tenacious of life, and very easily preserved. In this country they inhabit almost all our rivers, lakes, and ponds ; they are in great esteem for the table, and the consumption in our large cities is very considerable. The London market is principally supplied from Holland by Dutch fishermen. There are two companies in Holland, having five vessels each : their vessels are built with a capacious well, in which large quantities of Eels are preserved alive till wanted. One or more of these vessels may be constantly seen lying off Billingsgate ; the others go to Holland for fresh supplies, each bringing a cargo of 15,000 to 20,000 pounds' weight of live Eels, for which the Dutch merchant pays a duty of 1 3l. per cargo for his permission to sell. Eels and Salmon are the only fish sold by the pound weight in the London market.
Eels are not only numerous, but they are also in great request, in many other countries. Ellis, in his Polynesian Researches, vol. ii. page 286, says "In Otaheite, Eels are great favourites, and are tamed and fed until they attain an enormous size. These pets are kept in large holes, two or three feet deep, partially filled with water. On the sides of these pits they generally remained, excepting when called by the person who fed them. I have been several times with the young chief, when he has sat down by the side of the hole, and, by giving a shrill sort of whistle, has brought out an enormous Eel, which has moved about the surface of the water, and eaten with confidence out of its master's hand."
" Most of the writers on the habits of the Eel have described them as making two migrations in each year: one in the autumn to the sea ; the other in spring, or at the beginning of summer, from the sea. The autumn migration is performed by adult Eels, and is believed to be for the purpose of depositing their spawn ; it is also said that these parent fish never return up the rivers. The spring migration is commonly supposed to be confined to very small Eels, not more than three inches in length, and in reference to the fry alone, it is too well known, and too often recorded, to be matter of doubt. The passage of countless hundreds of young Eels has been seen and described as occurring in the Thames,* the Severn, the Parrett, the Dee, and the Ban. I am, however, of opinion, that the passage of adult Eels to the sea, or rather to the brackish water of the estuary, is an exercise of choice, and not a matter of necessity ; and that the parent Eels return up the river as well as the fry."
" All authors agree that Eels are extremely averse to cold. There are no Eels in the arctic regions, - none in the rivers of Siberia, the Wolga, the Danube, or any of its tributary streams ; yet the rivers of the southern parts of Europe produce four species. There is no doubt that fishes in general, and Eels in particular, are able to appreciate even minute alterations in the temperature of the water they inhabit. The mixed water they seek to remain in during the colder months of the year is of a higher temperature than the pure fresh water of the river, or that of the sea. It is a well-known law in chemistry, that when two fluids of different densities come in contact, the temperature of the mixture is elevated for a time in proportion to the difference in density of the two fluids, from the mutual penetration and condensation. Such a mixture is constantly taking place at the mouths of rivers that run into the sea, and the mixed water maintains a temperature two degrees warmer than that of the river or the sea. This elevation in the temperature of the water of estuaries and the mouths of rivers is, I have no doubt, one reason why they in general abound in young fish."
In a tideway river the descent of the Eels towards the brackish water takes place during the autumn, and various devices are employed in different streams to intercept them in their progress. The vignette at the bottom of the next page represents the form of an apparatus used in various parts of the Thames, called an Eelbuck, consisting of a framework of wood supporting various wicker-baskets of a particular form. The large open end of each basket is opposed to the stream, and by the peculiar structure of the inside, any fish once within the body of the basket, cannot escape.
During the cold months of the year Eels remain imbedded in mud ; and large quantities are frequently taken by Eelspears in the soft soils of harbours and banks of rivers, from which the tide recedes, and leaves the surface exposed for several hours every day. The Eels bury themselves twelve or sixteen inches deep, near the edge of the navigable channel, and generally near some of the many land-drains, the water of which continues to run in its course over the mud into the channel during the whole time the tide is out. In Somersetshire the people know how to find the holes in the banks of rivers in which Eels are laid up, by the hoar-frost not lying over them as it does elsewhere, and dig them out in heaps. The practice of searching for Eels in mud in cold weather is not confined to this country ; Dr. Mitchill, in his paper on the Fishes of New York, published in the Transactions of the Literary and Philosophical Society of that city, says, " In the winter Eels lie concealed in the mud, and are taken in great numbers by spears." Thus imbedded in mud, in a state of torpidity, the Eel indicates a low degree of respiration. Dr. Marshall Hall has shown that the quantity of respiration is inversely as the degree of irritability. With a high degree of irritability and a low respiration, co-exist - 1st. The power of sustaining the privation of air and of food ; 2nd. A low animal temperature ; 3rd. Little activity ; 4th. Great tenacity of life. All these peculiarities Eels are well known to possess. The high degree of irritability of the muscular fibre explains the restless motions of Eels during thunder-storms, and helps to account for the enormous captures made in some rivers by the use of gratings, boxes, and Eel pots or baskets, which imprison all that enter. The power of enduring the effects of a low temperature is shown by the fact, that Eels exposed on the ground till frozen, then buried in snow, and at the end of four days put into water, and so thawed slowly, discovered gradually signs of life, and soon perfectly recovered.
The mode by which young Eels are produced appears to have long been a subject of inquiry, and the notions of the ancients as well as of some of the moderns were numerous and fanciful. Aristotle believed that they sprang from the mud ; Pliny, from fragments which were separated from their bodies by rubbing against rocks ; others supposed that they proceeded from the carcases of animals; Helmont believed that they came from May-dew, and might be obtained by the following process: -" Cut up two turfs covered with Maydew, and lay one upon the other, the grassy sides inwards, and thus expose them to the heat of the sun ; in a few hours there will spring from them an infinite quantity of Eels." Horse-hair from the tail of a stallion, when deposited in water, was formerly believed to be a never-failing source of a supply of young Eels. It was long considered certain that they were viviparous: this belief had its origin probably in the numerous worms that are frequently to be found in various parts of the bodies of Eels, sometimes in the serous cavities, at others in the intestinal canal. Rudolphi has enumerated eight different species of entozoa common to fresh-water Eels. The enormous number of young known to be produced by Eels is a good negative proof that they are oviparous ; viviparous fishes producing, on the contrary, but few young at a time, and these too of considerable size when first excluded. Having devoted time and attention to the close examination of numbers of Eels for many months in succession, the further details of which will be found in Mr. Jesse's second series of Gleanings in Natural History, I need only here repeat my belief that Eels are oviparous, producing their young like other true bony fishes.
" The sexual organ consists of two long narrow sacs extending one on each side of the air-bladder throughout the whole length of the abdominal cavity, and continued for two inches posterior to the vent. The membranes forming this tubular sac, secreting on the inner surface the milt of the male, and affording attachment for the ova in the female, are puckered or gathered along the line of junction to the peritoneal covering of the spine, and the free or loose floating edge is therefore thrown into creases or plaits like a frill. It is probably from this folded or convoluted appearance the sexual organs of the Eel have frequently been called fringes. By the kindness of my friends Mr. Clift and Mr. Owen, of the Royal College of Surgeons, I have had the pleasure of seeing some drawings belonging to the collection of John Hunter, in which these peculiarities of the sexual organs in the Eel are beautifully exhibited in various magnified representations."
Dr. Mitchill of New York, whose paper on Fishes has been already referred to, says, " the roes or ovaria of Eels may be seen by those who will look for them in the proper season, like those of other fishes."
Eels that have lain in brackish water all the winter under the constant influence of the higher temperature of that locality, probably deposit their spawn earlier in the spring than those which have passed the winter in places from which there existed for them no possible egress. In the Mole, the Wey, the Longford river, and in some large ponds, the Eels in the spring of 1833 did not deposit their spawn till near the end of April; but in two Eels from Sheerness received and examined on the 18th of May, the internal appearances induced me to believe that the roes had been passed some time. How long the ova remain deposited before the young Eel is produced, is, I believe, unknown. The duration of this interval is very variable in different fishes. The roe of the Herring, deposited at the end of October or the beginning of November, is said to become living fry within three weeks: the ova of Eels, the produce of which is very small, do not probably require a longer period. Both the parent Eels and the fry occupying the brackish water appear to have the power of going either to the salt water or to the fresh without inconvenience, from the previous preparation which the respiratory organs have undergone, and many of both are found in pure sea water : the great bulk of the young, however, certainly ascend the stream of the river, and their annual appearance in certain places is looked for with some interest. The passage of young Eels up the Thames at Kingston in the year 1832 commenced on the 30th of April, and lasted till the 4th of May ; but I believe I am correct in stating that few young Eels were observed to pass up the Thames either in the year 1834 or 1835. Some notion may be formed of the quantity of young Eels, each about three inches long, that pass up the Thames in the spring, and in other rivers the beginning of summer, from the circumstance that it was calculated by two observers of the progress of the young Eels at Kingston in 1832, that from sixteen to eighteen hundred passed a given point in the space of one minute of time. This passage of young Eels is called Eel-fare on the banks of the Thames, - the Saxon word signifying to go, to pass, to travel ;** and I have very little doubt that the term Elver, in common use on the banks of the Severn for a young Eel, is a modification or corruption of Eel-fare.
" When the Elvers appear in the Severn, they are taken in great quantities with sieves of hair-cloth, or even with a common basket, and, after being scoured and boiled, are offered for sale. They are either fried in cakes or stewed, and are accounted very delicious."
There is no doubt that Eels occasionally quit the water, and when grass meadows are wet from dew, or other causes, travel during the night over the moist surface in search of frogs and other suitable food, or to change their situation. Some ponds continually produce Eels, though the owners of these ponds are most desirous of keeping the water free from Eels, from a knowledge of their destructive habits towards the spawn and fry of other fishes. Other ponds into which Eels have been constantly introduced are obnoxious to them from some quality in the water ; and they are known to leave such places during the night, and have been found on their passage to other retreats. Dr. Hastings, in his Illustrations of the Natural History of Worcestershire, says at page 134 : " I will here mention a curious confirmation of the opinion in favour of the overland migration of Eels. A relative of the late Mr. Perrott was out in his park with his keeper near a large piece of water, on a very beautiful evening, when the keeper drew his attention to a fine Eel quietly ascending the bank of the pool, and with an undulating motion making its way through the long grass : on further observation he perceived a considerable number of Eels quietly proceeding to a range of stews, nearly the distance of a quarter of a mile from the large piece of water from whence they started. The stews were supplied by a rapid brook, and in all probability the instinct of the fish led them in that direction as a means of finding their way to some large river from whence their ultimate destination, the sea, might be obtained. This circumstance took place at Sandford Park, near Enstone."
That Eels breed also in the fresh water of inland rivers and lakes from which they are unable to visit the sea, is, I believe, certain. A constant supply for the table is obtained throughout the winter in these localities, as well as at other seasons, by gamekeepers and fishermen, who have charge of waters thus situated ; and no doubt exists in their minds that these Eels are bred in the places from which they are obtained, and of which the great variation that occurs in the size is an additional proof.
The Eel is a voracious feeder during certain months of the year. In winter the stomachs of those which I examined were empty: by the middle of March I found the stomachs of others distended with the larvæ of various insects, and the bones of small fishes. They are known to consume a large quantity of spawn, and will attack large Carp, seizing them by the fins, though without the power of doing them further injury. Occasionally they eat vegetable substances, and have been seen swimming about the surface of water, cropping the leaves of small aquatic plants. By means of a long and capacious air-bladder, Eels rise to various elevations in the water with great ease, and sometimes swim very high even in deep water. When Whitebait-fishing in the Thames, I once caught an Eel in the net in twenty-six feet depth of water, though the Whitebait-net does not dip more than about three feet below the surface.
Eels appear to be slow of growth, not attaining greater length than twelve inches during the first year, and do not mature roe till the second or third year. The sharp-nosed species, however, acquires a large size. I saw at Cambridge the preserved skins of two which weighed together fifty pounds ; the heaviest twenty-seven pounds, the second twenty-three pounds. They were taken on draining a fen-dyke at Wisbeach.
Ely is said to have been so named from rents being formerly paid in Eels : the lords of manors in the isle were annually entitled to more than 100,000 Eels. A stich or stick of Eels was twenty-five ; and the practice of stringing Eels on tough slender willow-twigs, put in at the gill-aperture and out at the mouth, still prevails in Dorsetshire among those who carry Eels about for sale from house to house ; one, two, or three pounds' weight being thus strung on a stick, to suit different customers. Elmore on the Severn obtained its name from the immense number of Eels which are taken there.

In a sharp-nosed Eel of twenty-two inches in length, three distances taken from the point of the lower jaw are to the whole length of the Eel as follows : - to the upper part of the base of the pectoral fin, as two to seventeen ; to the commencement of the dorsal fin, as two to seven ; and to the commencement of the anal fin, as nine to twenty-two. In a sharp-nosed Eel of twenty inches in length, the pectoral fin will be almost one inch, and the vent more than an inch, nearer the head than the same parts in a broad-nosed Eel of the same length.
The head is compressed, the top convex, depressed as it slopes forward: the eyes small, placed immediately over the angles of the mouth ; irides reddish yellow: the jaws very narrow, slightly rounded at the end ; the lower jaw the longest: nostrils with two openings on each side, one tubular, the other a simple orifice ; both jaws furnished with a narrow band of small teeth ; gape small ; various mucous pores about the mouth and other parts of the head ; gill-opening a small aperture immediately before and rather below the origin of the pectoral fin ; the scales on the body rather small: dorsal fin extending over more than two-thirds of the whole length of the fish ; anal fin occupying more than half of the whole length ; both united at the end, forming a tail ; the number of rays in the fins not easily ascertained, from the thickness of the skin the lateral line exhibits a long series of mucous orifices ; vertebrae 113. The vent includes four distinct openings, the most anterior of which leads upwards to the intestine, the posterior to the urinary bladder in a direction backwards, and one elongated lateral opening on each side communicating with the cavity of the abdomen, as in other bony fishes.
The cranium on the right hand of the three, figured at page 303, is that of the sharp-nosed Eel.
The prevailing colour of all the upper surface is a dark olivaceous green ; the sides lighter; the belly white. When the fish are obtained from pure streams, the colours are clear and bright, and it is called a Silver Eel ; when taken from water over a muddy bottom, the colours are brown and dusky.
Dr. Marshall Hall, in 1831, while pursuing some physiological investigations on the circulation of the blood in various reptiles and fishes, observed a pulsating sac near the tail of the Eel. The form, action, and connexions of this sac are best seen under the microscope. A young Eel of six or seven inches in length, if rolled up in a strip of linen cloth, leaving out a small portion only of the tail, will remain quiet when placed on a long slip of glass, or may be tied to it with thread. The pulsation observed in this sac is entirely independent of the action or influence of the heart, and the number of beats more than double in the same period of time ; they also continue after the heart has been removed. Some Continental physiologists have ascertained that these pulsating sacs, which are found in the frog, the toad, the salamander, and the green lizard,*** contain lymph, and direct its motion, and they have accordingly called them lymphatic hearts. They are only observed in connexion with veins. " Such is," says Dr. Muller, " the pulsating organ discovered by Dr. Marshall Hall at the end of the vena caudalis of the Eel, where that organ receives the venous branches of the extremity of the tail, and conducts its blood into the vena caudalis. But organs of pulsation in the lymphatic system have hitherto been altogether unknown ; it is not probable that they should exist only in amphibia, and important discoveries of a like nature in the higher animals, such as birds and rnammalia, may be expected ; my researches, as regards these, have however been hitherto unsuccessful." In another part of his paper, Dr. Muller observes, " I have never discovered a trace of motion in the cysterna chyli and ductus thoracicus of mammalia."
In a conversation with Mr. Owen on this subject, he suggested, that as the valves of the lymphatic vessels are very few and imperfect in reptiles and fishes, especially in the latter, these pulsating sacs would seem to be superadded as a compensating power in the absence of that mechanism which impresses a definite direction and an unintermitting flow upon the currents of the lymph in the higher vertebrata, especially mammalia.
I am indebted to the kindness of Dr. Marshall. Hall for permission to copy the excellent illustration of this structure in the tail of the Eel, from his very interesting critical and experimental essay on the circulation of the blood.
In the vignette the arrow-heads indicate the direction of the currents.

* See an excellent account by Dr. William Roots, of Kingston, published in the second series of Gleanings in Natural History, by Edward Jesse, Esq. p. 50.
** A pedestrian on the road is called "a way-faring man ;" and hence, also, the price for travelling by a conveyance is called "the fare." We have also "thoroughfare," &c.
*** See a paper in the Philosophical Transactions for 1833, by Dr. John Muller, Professor of Physiology in the University of Bonn.

William Yarrell (1836) in "A History of British Fishes":

William Yarrell (1836) distinuishes three different species of fresh-water Eels
living in Great Brittain, the Sharp-nosed Eel, the Broad-nosed Eel and the Snig:

THE BROAD-NOSED EEL.

Anguilla	latirostris	Broad-nosed	Eel,	Yarrell, Proceed. Zool. Soc. 831, pp. 133 and 159. Zool. Journ. vol. iv. p. 469.
"	"	"	"	Jenyns, Man Brit. Vert. p. 476, sp. 164.
"	"	A.	pimperneaux,	Penn. Brit. Zool. vol. iii. p. 191.
Anguilla	vulgaris	"	"	Cuvier, Règne An. t. ii. p. 349.
"	"	Glut	Eel,	Bowdich, Brit. Fr. Wat. Fish, No. 22.

The Broad-nosed Eel is almost as common a species as the Sharp-nosed Eel, but is immediately distinguished from it by the much greater comparative breadth of the head ; the representation at the top of the page is therefore confined to that part of the fish which exhibits the best distinctions ; and the vignette to the Snig Eel, page 303, represents in the left-hand figure of the three heads the cranium of the Broad-nosed Eel, to show this character as it exists in the bone. This Eel is the Grig or Glut Eel of Pennant, who says, " They have a larger head, blunter nose, and thicker skin than the common sort." It is, probably, also the Frog-mouthed Eel of the Severn, referred to by Dr. Hastings, in his Natural History of Worcestershire, page 135, and so called by the fishermen from the extraordinary width of the mouth.
In its habits the Broad-nosed Eel has not been distinguished by any peculiarity that I am aware of from the other common Eel ; but it does not appear to attain so large a size, the largest I have seen not exceeding five pounds in weight. It exists in many of the waters which produce the Sharpnosed Eel, is much thicker in the body in proportion to its length, and fishermen can distinguish this species readily when fishing in the dark by its more soft and unctuous feel in the hand.
The term Grig is, however, in and about London, applied to a particular Eel of small size, of which the figure here introduced represents the head. This Eel is the Anguille plat-bec of Cuvier, Règne Animal, tom. ii. p. 349, who considers it a distinct species. It is the Grig Eel also of Mrs. Bowdich's British Fresh Water Fishes, No. 28, in which work the three Eels already spoken of here are well figured; and the species were considered by Cuvier as identical with those of the Règne Animal.

The name Grig is also applied by Thames fishermen to any small-sized Eel of any species when not longer than eight or nine inches, and of which eight or ten are required to make up a pound weight.
In a Broad-nosed Eel of twenty-two inches in length, three distances taken from the point of the lower jaw are to the whole length as follows : - to the upper part of the base of the pectoral fin, as two to thirteen ; to the commencement of the dorsal fin, as one to three ; and to the commencement of the anal fin, as ten to twenty-two.
The Broad-nosed Eel has the head rounded at the back part, and flattened from the eyes forward ; both jaws broad and blunt; the lower jaw the widest, and longer than the upper: nostrils double, one tubular, the other a plain orifice; the gape large ; lips fleshy: teeth more numerous than in either of the other British fresh-water species, larger, stronger, and forming a much broader band in each jaw : the eyes large, placed before the line of the gape ; irides golden yellow : the gill-openings, pectoral fins, the commencement of the dorsal fin and the vent, placed farther back than in the Sharp-nosed Eel; dorsal and anal fins also much deeper and thicker; the tail broad and rounded ; the body of the fish thicker for the same length than in other Eels: the number of vertebræ 115.
The colour of the upper surface of the body is a darkgreenish brown, subject to some variation, depending on locality, soil, and the quality of the water.

William Yarrell (1836) in "A History of British Fishes":

William Yarrell (1836) distinuishes three different species of fresh-water Eels
living in Great Brittain, the Sharp-nosed Eel, the Broad-nosed Eel and the Snig:

THE SNIG.

Anguilla	mediorostris	Snig	Eel,	Yarrell. Jesse, Glean. Nat. Hist. 2nd Series, pp. 75 and 76.
"	"	"	"	Jenyns, Man. Brit.Vert. p. 477, sp. 165.

I am indebted to the kindness of Mr. Jesse, and his friend, Francis Mills, Esq. for the only specimens of this Eel I have yet seen ; and from some differences in its external characters, in its habits, and also in the comparative size of the head, as well as some peculiarity in the five cervical vertebræ that are nearest the head, I believe it to be a different species from either of those previously described in this work.
The specimens I have had were from the Avon in Hampshire, where this Eel, rather remarkable for its yellow colour, is called the Snig, and is considered distinct from the other well-known and more common Eels.
Dr. Hastings, in the Appendix to his Illustrations of the Natural History of Worcestershire, page 135, says, that besides an Eel called the Frog-mouthed Eel by the fishermen, from the extraordinary width of the mouth, - identical, probably, with the Broad-nosed Eel of this work, - " there are two distinct kinds of Eels in the Worcestershire Avon, the Silver and Yellow Eel," which last may be similar to the Snig of the Avon of Hampshire.
The term Snig, it should however be stated, is in some counties a general name for any sort of Eel ; and a particular mode of fishing for Eels, which is described in most of the works on Angling, is called Sniggling.
The Hampshire Snig differs from our other Eels in its habit of roving and feeding during the day, which other Eels do not. It is considered excellent as an article of food, and of a superior flavour to other Eels : it does not however attain a large size, seldom exceeding half a pound in weight.
The fishermen make a certain difference in the mode of placing their eel-pots when they are desirous of catching Snigs ; finding by long experience that the Snigs get into those pots the mouths of which are set in the opposite direction, in reference to the stream, to others in which the common Eels are taken.
In the comparative breadth of the nose, the Snig is intermediate in reference to the Sharp and Broad-nosed Eels, but rather more resembles that with the sharp nose ; it has a slight but elongated depression extending from the anterior edge of the upper jaw to the upper and back part of the head ; the tubular openings of the nostrils are longer, and the mucous pores about the lips larger and more conspicuous; both jaws rounded at their extremities, the lower one the longest; teeth longer and stronger than in the common sharp nosed species ; gape large ; the angle and the posterior edge of the eye on the same vertical line ; the pectoral fins, the commencement of the dorsal fin, and the vent, are each placed nearer the head than in either of our fresh-water Eels.
The general colour olive green above, passing by a lighter green to yellowish white below.
Desirous of obtaining internal characters of distinction among our fresh-water Eels, I prepared skeletons of each species, selecting three examples that measured exactly the same length, in order to afford a more just comparison. The vignette at the bottom of the page represents correctly the relative size and power of bone in each species. The cranium on the left is that of the Broad-nosed Eel ; that in the middle is from the Snig; the head on the right hand is from the Sharp-nosed Eel. It is obvious that each is able to overcome a larger and more powerful victim as food than the other. It will also be seen, that independent of some difference in the length and form of some of the bones, as well as in the size of the head in the middle, belonging to the Snig, as compared with that on either side, there is a characteristic distinction in the form of the bones of the vertebral column. The first five cervical vertebræ are smooth and round, entirely destitute of superior or lateral spinous processes, both of which are possessed by the other two, of a size corresponding to the character of the vertebral bone itself to which it belongs. With this exception, the skeleton of the Snig most resembles that of the Sharp-nosed Eel ; but is somewhat stronger, and particularly so in the processes of the other vertebræ generally.

Frank Buckland (1880) in "Natural History of British Fishes":

EELS.

Anguillidæ

German : Der Aal. Swedish : Al. Dutch: De Paling. French: Anguille.

THERE are three or four distinct species of the freshwater eel inhabiting this country.
The Common or Sharp-nosed Eel, inhabits all our fresh waters, abounds throughout Europe, except in the Arctic regions, and in some of those rivers which have their source in very cold districts ; it is found in Asia also, and, in short, in almost every part of the world. The eels in New Zealand are very large.
The Broad-nosed Eel (Anguilla latirostris) is almost as common a species as the preceding. It differs in the shape of the head, which is much broader, the nose blunter, and the skin thicker than the common sort. It is probably the “Frog-mouthed eel” of the Severn, so called by the fishermen from the width of the mouth. It exists in many of the waters which produce the sharp-nosed eel, and is much thicker in the body in proportion to its length.
The Snig Eel (Anguilla mediorostris) is another species which occurs chiefly in the Avon, in Hampshire, where this eel, rather remarkable for its yellow colour, is considered distinct from the common sorts. There are some differences in its external formation and habits, as well as in the size and character of the bones. The Hampshire snig differs from the others in roving and feeding during the day-time, the other species being nocturnal. It is considered excellent as food, but does not attain a large size, seldom extending more than half a pound in weight.
The fishermen make a certain difference in the mode of placing their eel-pots when they are desirous of catching “snigs,” finding by long experience that the snigs get into those pots the mouths of which are set in the opposite direction, in reference to the stream, to those in which the common eels are taken. In the comparative breadths of the nose, the snig holds an intermediate position between the sharp and broad-nosed eels, rather more resembling the former. It has a slight but elongated depression, extending from the anterior edge of the upper jaw to the upper and back part of the head.
Eels are sometimes found of a lovely golden colour ; and I have also seen two specimens of albino eels, the skins being nearly white.

Various methods are resorted to to intercept eels while they are on their autumnal migrations. The apparatus used on the Thames, called an eel-buck (of which a figure is here given), consists of a number of wicker baskets supported on a wooden framework. The large open end of each basket is opposed to the stream, and, by the peculiar construction of the inside, which is like a mouse trap, a fish, having once entered, cannot escape again. A set of these eel-bucks can be seen from the bridge over the Thames to the east of Maidenhead station, on the Great Western Railway. In Land and Water, No. 383, May 24, 1873, have published diagrams and descriptions of eel-nets as used in the Severn between Gloucester and Worcester.
The eel fisheries in Ireland are exceedingly valuable ; very large numbers are caught in the autumn months, as they are descending from the lakes to the sea -- they generally run on nights when thunder is about -- and are put into boxes and screwed tightly down when alive. I consider this to be a most cruel proceeding ; the poor things must suffer very much screwed down in those dreadfully narrow quarters. This is a subject well worthy of the attention of the Society for the Prevention of Cruelty to Animals.
I have heard of an old Irish fisherman who used to set his eel-nets and then beat a drum. His reason was this: “Bedad, sir, it's just to make the eels run ; they think it's a thundery night.”
I have heard that the eel fishery at Ballisodare, in Ireland, has been greatly improved and increased in annual value by making a pass for elvers over a natural obstruction. This is done by placing ropes of straw loosely plaited, up which the elvers climb. This is a hint that may be useful to other proprietors of eel fisheries. I have much more to write about elvers, but have not space.
The London market is principally supplied from Holland, the eels being brought over in Dutch vessels. A free mooring was given to these Dutch skoots by Queen Elizabeth, and boats have taken advantage of this privilege up to the present day.
In various localities eels run to a large size, some of the weights of which are recorded in various numbers of Land and Water. Thus, one was taken at Tewkesbury weighing 7½lbs. ; at Stag Park, Petworth, one of 5lbs.; in the Arun, one of 4½lbs., and another of 9lbs. ; in the Richmond Round Pond one of 5lbs. 14oz. ; at Bulford Mill, one of 4lbs., which had been seen to draw the young ducks down into the water. In one of the broads near Great Yarmouth an eel was taken in a tench bow-net of 7lbs., and in the same broad one of 6lbs. and 6½lbs. ; another near the New Mills, Norwich, turned the scale at 7¼lbs. ; another on 13th January, 1869, in the very same spot, of 8½lbs. Eels of 5lbs. and 8lbs. are not uncommon in Norfolk. An eel was taken in 1869 in the Ouse (Hunts), at St. Ives Staunch, 7lbs. ; and two of 6lbs. each about the same time at Hemingford Grey Mills, on the same river.
In the year 1850 an eel of 8¾lbs. was taken from the pond of Dutford Mill, and twenty-one eels were taken out of the eel-trap at the same place, whose united weight amounted to 84lbs., and one of the eels was not 6oz. in weight.
The largest fresh-water eel I ever examined and cast was a magnificent specimen sent in May, 1878, by Mr. John Welch, eel salesmen, Billingsgate. It measured 4ft. 4in. in length, 10in. round and weighed just upon 10lbs. It was taken in the river Mole.

STRUCTURAL BEAUTIES OF THE EEL.

I am happy to find that among anglers there is gradually spreading a desire to know much more of the actual structure and physiology of fishes than heretofore, and it always gives me great pleasure, when I have an opportunity, of pointing out any structural peculiarity which exemplifies Paley's argument of the wonderful adaptation of means to ends. In the common eel we have an excellent example of this. The eel, as is well known, will live a long time out of water. This habit is of the greatest service to him, as sometimes it is necessary for him to migrate from place to place by an overland route. To enable him to live out of the water the eel has a most elaborate yet simple form of mechanism, by means of which he is enabled to keep his gills moist even though he is not in the water. It will be observed that immediately, or if not very soon after, an eel is taken out of the water, two great swellings will take place each side of the head, and that if the eel is placed back in the water this swelling will immediately disappear. Let us now take a dead eel ; we shall find close to the pectoral fins a slit in the skin which acts as a valve. If we take a probe and pass it through this slit we find that it enters a large cavity ; next, take a pair of scissors and cut open this cavity, inside we shall find the gills proper. It is this cavity which the eel has the marvellous power of filling with water, and keeping a supply which shall not allow the gill fibres to adhere together, and thence of necessity stop respiration. This cavity is of course made of a large and loose skin-like membrane, which holds the required quantity of water; but in order to enable him to fill and empty this cavity, an elastic yet firm mechanism of some kind is absolutely necessary.
See for yourselves what a beautiful piece of machinery is provided by the Creator. A framework of very delicate bones, each bone connected with its neighbour by an elastic membrane of the consistency of goldbeaters’-skin, forms a fan-shaped covering over the gills; its action is very like, if not exactly the same as, the action of an umbrella. When the eel wishes to take in his water-supply he, as it were, opens the umbrella-shaped framework and fills his reservoir; when he wishes to expel the water he, as it were, closes his umbrella, as his reservoir is no longer required to come into action.
If an eel be taken out of the water and placed on the floor of a room, and left there for some time, it will be seen that he will very soon expand his reservoir. After a time he will be desirous to refill his reservoir; take him up and put his head into a basin, you will see that he will immediately take two or three great gulps so as to restock his breathing bags. It is by this beautiful piece of mechanism that the eel is enabled to live so much longer out of water than any other fish; and also, as I have stated before, to shift his quarters when it is desirable to do so.
There is another point in his structure well worthy of observation -- it is the spectacles of the eel. The eel has to live amongst mud, stone, &c., and if his eyes were not protected, it is reasonable to suppose that its delicate structure would occasionally get wounded.
Over the eye, therefore, we find a wonderful eyeglass. This is formed by the ordinary scale-covered skin of the head, just at the point where it passes over the eye, taking the form of a thin but strong transparent membrane, which affords an admirable guard against any injury occurring to the organs of sight. The eye itself is a very beautiful round ball, the iris black pencilled with tints of a golden hue. If the eyeball be cut in two the lens will immediately pop out, the most lovely little crystal ball, in brilliancy equal, if not superior to, a diamond. The reader should dissect off for himself these curious spectacles of the eel ; by drying the skin of the head on a piece of window-glass their structure will at once be seen.
The common snake has a somewhat similar provision, only, whereas he lives on dry land, his spectacles have a firmer and horny consistency. The structure of the snakes’ eye-glasses may be easily seen in the shed skin of the snake (and snakes shedding their skin frequently during the year). When the snake sheds his skin it is found turned inside out. Thus the transparent eye-protectors easily become discernible.
A question has often arisen as to whether eels have or have not scales. Again look for yourself. Place a portion of an eelskin on a microscope slide or window-glass and as it dries you will see quite plainly the scales come into view as the slimy membrane in which they are imbedded gradually dries up. These scales are of an oval shape, somewhat resembling carraway seeds. They are arranged in very pretty patterns, much resembling the so-called herring-bone pattern in which ornamental titles are sometimes placed.
The eel also has, strange to say, a heart in his tail. If it is desired to ascertain this fact it is only necessary to observe, that eels which are so frequently sold in the streets are covered with sand. When the eel becomes faint and exhausted he will begin to play up the lymphatic heart in his tail, the pulsations of which can be seen.

The remaining species of the eel family are, the Anglesea Morris (Leptocephalus morrisii), a small ribandshaped fish, of extremely delicate texture, being semi-transparent. It is about five or six inches long, and in thickness does not exceed the sixteenth part of are inch. It is regarded as a rare visitor; but Mr. Couch says, that off the Cornish coast it is taken so frequently that it cannot be uncommon in deep water. It is usually found entangled among sea-weed. The illustration on previous the page is a copy of the figure given of it.

Alwyne Wheeler (1969) in "The Fishes of the British Isles and North West Europe":

Eel

Anguilla anguilla (Linnaeus, 1758)

NAMES Fr. Anguille; Du. Paling, Aal; Ge. Aal, Flussaal; Da. & Nor. Aal.

IDENTIFICATION The lower jaw is noticeably longer than the upper and protrudes; the eye is always rounded, small in young and yellow eels, large in silver eels; the pectoral fin is small and rounded and the dorsal fin originates far behind the pectorals. It has minute scales embedded in the skin, in contrast to the conger which is scaleless.
The colour varies from black to grey-brown on the back and sides, and the belly is yellow; the fins are yellow or cream. except the dorsal fin which is dark. In individuals approaching sexual maturity the sides and belly are bright silvery, and the eye may be greatly enlarged. Very rarely orange coloured specimens are reported.
D. 245-75; A. 205-35; vertebrae 112-17.
It grows to a maximum length of 54 in (37 cm) and a weight (exceptionally) of 20 lb (9 kg); most are a good deal smaller.

BIOLOGY The eel's life history has been much discussed and carefully studied and yet there is today still much that is unknown or imperfectly known about this common and familiar fish.
Eels are common in most rivers and their estuaries in northern Europe and on the whole of its seaboard. In these waters they are mainly nocturnal in activity, lying up during the day under cover or in weed beds. In estuaries and at sea on soft bottoms they bury themselves in sand or mud, and they are are very common where suitable pools exist between tide marks, and below. As a general rule the eels found in the sea and in estuaries are small, but occasionally large ones are encountered. It has been claimed that the eels in marine habitats are males, while the freshwater eels are females and attain a larger size, but this does not appear to be always true. Some males are found in fresh water, and some female yellow eels, up to 30 in (76 cm) in length, are encountered in wholly marine habitats. It is probable that many large maturing eels of both sexes live in inshore waters, but have not been encountered due to some specialised habit, and to our generally inefficient means of collecting.
After metamorphosis the elvers ascend rivers or take to life in the littoral zone at a length of about 3 in (7 cm). On the Biscay coast they ascend rivers from October to December, on the western French and Irish coasts in January, in the Channel, Irish Sea and Scottish coasts in February, in the North Sea and the entrance to the Baltic in March and April. They spend a considerable time in freshwater feeding and growing; males spending from seven to twelve years (on average nine), females from nine to nineteen years (on average twelve). These figures are from northern England. At these age ranges the females measure from 18 to 37 in (46-94 cm) and the males 14 to 17 in (36-43 cm).
In fresh water the eel's diet is composed almost entirely of bottom-living invertebrates, chiefly molluscs, and insect larvae (Trichoptera, chironomids and Coleoptera). Crustaceans and fish are rarely eaten, and although fish may feature in the diet of large eels they are usually bottom-living forms such as gudgeon, bullhead, stone loach, lamprey, burbot and stickleback. There is little evidence that eels prey upon salmonid fishes, although some may be eaten on occasions. They do, however, compete with both young trout and young salmon for food, although the degree of competition varies with the size of population and the time of year.
Those eels in fresh water are known as yellow eels, but many other names in the United Kingdom (broad-headed, sharp-nosed, grig, frog-mouthed) and Europe have been applied to stages in the development, or to fancied differences between them.
When the male yellow eels reach a length of 16 in (41 cm) and the females 21-4 in (54-60 cm) they begin migrating to the sea. It is at this time that they may travel overland for short distances, in the autumn, usually only when the ground is very wet. Movement is largely confined to moonless or dark nights and usually in flood water after heavy rain. At this period the colour of the eel also changes, the dark hue of the back becoming more intense, and the sides and belly metallic silver, the eye enlarges and the gonads begin maturing. In September and October these silver eels are at their most abundant at river mouths, and are extensively caught in fixed traps.
Very little is known of their oceanic migration, as few silver eels have been taken at sea. The eye is greatly enlarged, the gut atrophies, the jaws weaken and the gonads increase in size. They are believed to swim in mid-water and possibly at the surface at night. Spawning takes place in spring and early summer, in an area in the western Atlantic (22-30° N. and 48-65° W.). The eggs probably float in mid-water, for the youngest larvae are abundant in this area from March to July. Thereafter, eel leptocephali (Fig. 84) of gradually increasing length can be caught to the west and north-west of the spawning area, their dispersal being mainly due to passive drift in the north-easterly moving ocean currents. Metamorphosis from leptocephalus to a transparent, eelshaped 'glass eel' takes place in the ocean, probably over the continental shelf, and they arrive on European coasts after two and a half to three years. These glass eels undergo what has been called a second metamorphosis when pigment cells form in the skin and gradually a fully coloured elver is formed. This second metamorphosis takes place in coastal waters. These elvers are found most abundantly in the rivers with direct access to the Atlantic.

Fig. 84

In 1958 an alternative theory was advanced, that for physiological reasons the European eels fail to return to the spawning ground in the western Atlantic, and that our eels are the progeny of American parents; the American species is known as Anguilla rostrata Le Sueur, 1821. Such differences as were known to exist between these species, for example in vertebral numbers, were explained as being due to the physical conditions of the water during the critical period of their early development. This ingenious theory has not attained wide acceptance, and it has been shown recently that the differences between the two Atlantic Anguilla species is greater than was at one time appreciated.
The European eel is a valuable food fish, taken in trawls and on long-lines as a yellow eel, and in traps of various kinds as a migrating silver eel. The fisheries are locally very valuable, but as they depend on recruitment by migration of the young and as the eels spend so long in fresh water, they are highly susceptible to over-exploitation. The eel is also a favoured angling fish; its size, wide distribution and readiness to take a bait make the female yellow eel a worthwhile fish, although the intentional capture of large eels is a specialised field. The British record rod-caught fish weighed 81 lb (3.85 kg).

DISTRIBUTION

Also Mediterranean, Black Sea and North African coast to the Canaries, Madeira and the Azores.

Eel

Izaak Walton (1653) in "The Compleat Angler":

"Observations of the Eel, and other fish that want scales; and how to fish for them."

Chapter XIII. [Fourth day]