18 



FUNCTIONS OF FISHES. 



greater number of them, consequently, remain at the bottom, unless the fcrm of their 

 body enables them to strike the water downwards with great force. This the Skate, 

 the Thornback, and other species of Rays do with their large pectoral fins, which 

 are of such size and strength as almost to resemble wings ; and the mode in which 

 these fish elevate themselves in the water, is precisely the same as that which ia 

 employed by birds in flying. 



The teeth of fish are usually situated in their jaws : in some species, however, 

 there are teeth on the tongue and palate, and even in the .throat. These are 

 generally sharp-pointed and immovable ; but in the Carp they are obtuse, and in the 

 Pike so movable as to appear fixed only to the skin. The tongue is in general 

 motionless and fleshy. Being furnished with nostrils and olfactory nerves, there can 

 bu little doubt that fishes possess the sense of smelling. 



The bones of these animals are formed of a kind of intermediate substance, between 

 true bones and cartilages. The back-bone extends through the whole length of the 

 body, and consists of vertebrae, strong and thick toward the head, but weaker and 

 more slender as they approach the tail. The ribs are attached to the processes 

 of the vertebrae, and enclose the breast and abdomin. Several fish, as the Bays, 

 have no ribs ; and others, as the Eel and Sturgeon, have very short ones. In 

 many of the species there are small bones between the muscles, to assist their motion. 



The sight of fishes is perhaps the most perfect of all their senses. The eye, in 

 general, is covered with the same transparent skin that covers the rest of the 

 head ; the use of which is probably, to defend this organ in the water, for none of the 

 species have eyelids. The globe of the eye is somewhat depressed in front, and it is 

 famished behind with a muscle, which serves to lengthen or flatten it, as the animal 

 may require. The crystalline humor, which in quadrupeds is flattened, is in fishes 

 nearly globular. The eyes of fish are usually thought to be immovable, but thia 

 does not appear to be the case : those of some species are known to turn in tha 

 sockets. 



In fishes the organ of hearing is placed at the sides of the skull ; but differing in 

 this respect *'rom that in quadrupeds and birds, it ia entirely distinct and detached 

 from it. In some fishes, as those of the Ray kind, the organ of hearing is wnol'j 

 surrounded by the parts containing the cavity of the skull : in others, as the Salmon 

 and Cod, it is partly within the skull. In its structure this organ is by no means 

 so complicated as in quadrupeds and other animals that live in the air. Some 

 genera, as the Rays, have the external orifice very small, and placed upon the upper 

 surface of the head ; but in others there is no external opening whatever. 



The food of these animals is extremely various. Insects, worms, or the spawn of 

 other fish, sustain the smaller tribes ; which, in their turn, are pursued by larger foes. 

 Some feed on mud and aquatic plants, but by far the greater number subset on 

 animal food only, and they are so ravenous as often not to spare even those of their own 

 kind. Innumerable shoals of some species pursue those of others through vast 

 'tracts of the ocean ; from the vicinity of the pole sometimes even to the equator. 

 In these conflicts, and in this scene of universal rapine, many species must have 

 become extinct, had not the Creator accurately proportioned their means of escape, 

 their production, and their numbers, to the extent and variety of the dangers to 

 which they are exposed. The smaller species are consequently not only more nu- 

 merous and prolific than the larger, but their instinct impels them to seek for food 

 and protection near the shore, where, from the shallowness of the water, many of 

 their foes are unable to pursue them. 



Fishes are in general oviparous : some few, however, produce their offspring alive. 

 The males have the milt, and the females the roe, but some individuals of the Cod 

 und Sturgeon tribes are said to contain both. The spawn of the greater number ia 

 deposited in the sand or gravel : many of the fish, however, which reside in the ocean, 

 attach their ova to sea-weeds. The fecundity of these tribes far surpasses that of 

 any other race of animals. In the spawn of a single Cod upwards of nine millions 

 of eggs have been ascertained, and nearly a million aid a half have been taken from 

 the interior of a Flounder. 



The longevity of fish is far superior to that of other creatures ; and there is reason 

 to suppose that they are, in a great measure, exempted from disease. Instead of 

 Buffering from the rigidity of age, which is the cause of natural decay in land animalci, 

 their bodies continue to increase with fresh supplies ; and, as the body grows, the 

 conduits of life seem to furnish their stores in greater abundance. How long these 



