368 



HISTORY OF FISHES. 



this substance the natives of Palermo sometimes 

 make gloves and stockings. 



These shell-fish are found in lakes, rivers, 

 and in the sea. Those of the lake often grow 

 to a very large size ; but they seem a solitary 

 animal, and are found generally separated 

 from each other. Those of rivers are not so 

 large, but yet in greater abundance ; but the 

 sea-mussel of all others is perhaps the most 

 plenty. These are often bred artificially in 

 salt-water marshes that are overflowed by the 

 tide , the fishermen throwing them in at the 

 proper seasons; and there being undisturbed 

 by the agitations of the sea, and not preyed 

 upon by their powerful enemies at the bottom, 

 they cast their eggs, which soon become per- 

 fect animals, and these are generally found in 

 clusters of several dozen together. It requires 

 a year for the peopling of a mussel bed ; so 

 that, if the number consists of forty thousand, 

 a tenth part may annually be left for the 

 peopling the bed anew. Mussels are taken 

 from their beds from the month of July to Oc- 

 tober ; and they are sold at a very moderate 

 price. 1 



From this animal the oyster differs very 

 little, except in the thickness of its shell, and 

 its greater imbecility. The oyster, like the 

 mussel, is formed with organs of life and res- 

 piration, with intestines which are very volu- 

 minous, a liver, lungs, and heart. Like the 

 mussel, it is self-impregnated ; and the shell, 

 which the animal soon acquires, serves it for 

 its future habitation. Like the mussel, it 

 opens its shell to receive the influx of water ; 

 and like that animal is strongly attached to its 

 shell both above and below. 



But it differs in many particulars. In the 

 first place, its shells are not equal, the one 

 being cupped, the other flat: upon the cupped 

 shell it is always seen to rest ; for if it lay 

 upon the flat side it would then lose all its 

 water. It differs also in the thickness of its 

 shells, which are so strongly lined and defen. 



1 Some shell-fish are poisonous when eaten. This is 

 frequently the case with mussels. In the month of June, 

 1827, a great number of the poor in Leith were poisoned 

 by eating these shell-fish, which they procured from the 

 docks. " The town," says Dr Combe, " was in a ferment, 

 and the magistrates, with great propriety, issued a warn- 

 ing against the use of the mussels. Many deaths were 

 reported, and hundreds of individuals were stated to be 

 suffering under it. Luckily, matters were not so de- 

 plorable ; but we ascertained that in addition to the man 

 mentioned before, the companion of our patient, an el- 

 derly woman, had died. In all, about thirty cases oc- 

 curred, with great uniformity of symptoms, but varying 

 very much in severity : but none, so far as I know, have 

 left any permanent bad effects." To what (ftuse these 

 deleterious effects are to be ascribed is uncertain. Some 

 attribute them to disease in the fish, or to its being in a 

 state of putrefaction ; others to its having fed on some 

 poisonous articles, more particularly on tho ores of 

 copper. 



ded, that no animal will attempt to pierce 

 them. But though the oyster be secured from 

 the attacks of the small reptiles at the bottom, 

 yet it often serves as an object to which they 

 are attached. Pipe-worms, and other little 

 animals, fix their habitation to the oyster's 

 sides, and in this manner continue to live in 

 security. Among the number of these is a 

 little red worm, that is often found upon the 

 shell ; which some, from never seeing oysters 

 copulate, erroneously supposed to be the male 

 by which their spawn was impregnated. 



The oyster differs also from the mussel, in 

 being utterly unable to change its situation. 

 The mussel, as we have observed, is capable 

 of erecting itself on an edge, and going for- 

 ward with a slow laborious motion. The oys- 

 ter is wholly passive, and endeavours by all 

 its powers to rest fixed to one spot at the bot- 

 tom. It is entirely without that tongue which 

 we saw answering the purposes of an arm in 

 the other animal; but nevertheless is often at- 

 tached very firmly to any object it happens to 

 approach. Rocks, stones, pieces of timber, or 

 sea-weeds, all seem proper to give it a fixture, 

 and to secure it against the agitation of the 

 waves. Nothing is so common in the rivers 

 of the tropical climates as to see oysters grow- 

 ing even amidst the branches of the forest 

 Many trees which grow along the banks of 

 the stream often bend their branches into thf 

 water, and particularly the mangrove, which 

 chiefly delights in a moist situation. To these 

 the oysters hang in clusters, like apples upon 

 the most fertile tree ; and in proportion as the 

 weight of the fish sinks the plant info the 

 water, where it still continues growing, the 

 number of oysters increase, and hang upon the 

 branches. Thus there is nothing that these 

 shell-fish will not stick to ; they are often even 

 found to stick to each other. This is effected 

 by means of a glue proper to themselves, 

 which, when it cements, the joining is as hard 

 as the shell, and is as difficultly broken. The 

 joining substance, however, is not always of 

 glue ; but the animal grows to the rocks, 

 somewhat like the mussel, by threads ; al- 

 though these are only seen to take root in- the 

 shell, and not, as in the mussel, to spring from 

 the body of the fish itself. 



Oysters usually cast their spawn in May, 

 which at first appear like drops of candle- 

 grease, and stick to any hard substance they 

 fall upon. These are covered with a shell in 

 two or three days ; and in three years the ani- 

 mal is large enough to be brought to market. 

 As they invariably remain in the places where 

 they are laid, and as they grow without any 

 other seeming food than the afHux of sea-water, 

 it is the custom at Colchester, and other parts 

 of the kingdom, where the tide settles in 

 marshes on land, to pick up great quantities of 



