CHAP. 14. (12.)—DISTRIBUTION OF AQUATIC ANIMALS INTO VARIOUS SPECIES.

The integuments of the aquatic animals are many in num- ber. Some are covered with a hide and hair, as the sea-calf and hippopotamus, for instance; others again, with a hide only, as the dolphin; others again, with a shell,[1] as the turtle; others, with a coat as hard as a stone, like the oyster and other shell-fish; others, with a crust, such as the cray-fish; others, with a crust and spines, like the sea-urchin; others, with scales, as fishes in general; others, with a rough skin, as the squatina,[2] the skin of which is used for polishing wood and ivory; others, with a soft skin, like the muræna;[3] and others with none at all, like the polypus.[4]

1. The Latin is "cortex," which probably means a "bark," or "rind." Ajasson remarks upon the meagreness of the Latin language, in supplying appropriate words for scientific purposes, and congratulates himself upon adding the word, "carapax," (signifying "callipash," as we call it) to the Latin vocabulary.

2. By us known as the "angel-fish," the "Squalus squatina" of Linnæus, a kind of shark. From this property of its skin, it was called by the Greeks r(inh, the "file." See B. xxxii. c. 53.

3. Probably the Muræna helena of Linnæus. See more on it in c. 23 of the present Book.

4. Spoken of more fully in c. 23 of this Book.