Lamprey, or Petromyzon, L. a genus of fish comprising three species, which are chiefly distinguished by their peculiar back fins.

1. The marinus, or Sea Lamprey, which, in shape, resembles an eel, has small eyes, covered with a light blue membrane, and the pupil is encompassed with a gold-coloured ring. During cold weather, this fish conceals itself in the crevices of rocks ; on the pebbly edges of which it is an usual expedient among anglers, to form pits extending to the water-side : into these a little blood is thrown, to induce the lamprey to put forth its head between two rocks. As soon as the hook, which is to be baited with crab, or some other fish, is presented, it is greedily swallowed, and thus the prey is easily taken.

2. The fluviatilis, or Lesser Lamprey ; the mouth of which is like that of the preceding, but.the colour of its back is either brown or dusky, sometimes mixed with blue, the whole underside being silvery.

These fish sometimes grow to the length of ten inches, are found in the rivers Thames, Severn, and Dee ; are potted with the larger kind, and occasionally preferred, on account of their milder flavour.—. Vast quantities are taken about Mortlake, and sold to the Dutch, who employ them as bait for their cod fishery. It is computed that above 430,000 have in one season been vended to them at 40s. per thousand; as they possess the secret of preserving the lamprey till the turbot fishery commences.

3. The bronchialis, or Lam-pern, which is found in the Isis, near Oxford, and other British rivers ; it is about eight inches long, and the body does not exceed the thickness of a swan's quill.—Unlike the other species, lamperns conceal themselves in the mud, and never adhere to stones, or other matters.

The flesh of these fish, in general, is white, fat, soft, and easy of digestion : it has an agreeable taste, and is not less nutritive, though more wholesome, than that of the eel: those of a large size, however, possess a superior flavour.