286 



HISTORY OF FISHES. 



facture of such productions as thrive more rea- 

 dily among us. Were, for instance, the num- 

 ber of hands that we have now employed in 

 the manufacture of silk, turned to the increase 

 of agriculture, it is probable that the increased 

 quantity of corn thus produced, would be more 

 than an equivalent for the diminution of na- 

 tional wealth in purchasing wrought silk from 

 other countries 



CHAP. VI. 



OP ANOMALOUS CARTILAGINOUS FISHES. 1 



OF all others, the Cartilaginous class seems 

 to abound with the greatest variety of ill- 



1 Eels . The general appearance of the Eel is so well 

 known, and so unlike that of mo?t other fishes, as to require 

 but a slight description ; yetit 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 

 Regne 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 no- 

 tice 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 simi- 

 larity 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 exter- 

 nal 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 ly- 

 ing off Billingsgate ; the others goto Holland for fresh 

 supplies, each bringing a cargo of 15,000 to 20,000 

 pounds' weight of live eels, for which the Dutch mer- 

 chant pays a duty of 13 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 Polyne- 

 sian 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 re- 

 mained, excepting when called by the person who fed 

 them. I have been several times with the young chief, 



formed animals ; and, if philosophy could al- 

 low the expression, we might say, that the 

 cartilaginous class was the class of monsters ; 

 in fact, it exhibits a variety of shapeless beings, 



when he has sat down by the side of the hole, and, by 

 giving a shrill sort of whistle, has brought out an enor- 

 mous 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 con- 

 fined 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 ap- 

 preciate 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 con- 

 tact, 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 condensa- 

 tion. 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 tem- 

 perature of the water of estuaries and the mouths of ri- 

 vers 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 va- 

 rious devices are employed in ditferent streams to inter- 

 cept them in their progress. One apparatus used in va- 

 rious parts of the Thames, called an eelbuck, consists 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 im- 

 bedded in mud; and large quantities are frequently 

 taken by eel-spears 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 So- 

 mersetshire the people know how to find the holes in the 

 banks of rivers in which eels are laid up, by the hoar- 



