3. Cyclostomi (Round-mouthed).
FIG. 46.—THE LAMPREY (Petromyzon fluviatilis)
(b, the sucker).
The Lamprey or Lampern (fig. 46) inhabits both rivers and lakes, and some species, the sea; it has a round mouth, by which it affixes itself to rocks, &c., and also to other fish, it is furnished with teeth on the outer edge, it has no scales, but is covered with a glutinous skin; in form it much resembles an Eel, and is from twelve to eighteen inches long. The Lamprey was once very plentiful in the Thames, and considered a dainty.
REPTILES.
These constitute the second class of the Vertebrate animals. They are divided into four orders.
FIG. 47.—1, FROG (Rana temporaria). 2, TOAD (Bufo vulgaris). 3, TADPOLES.
1. Amphibia (double-lived).