BRITISH FRESH-WATER FISHES
also stated to partake of insects and worms. The manner of propulsion through the water reminds one of the movements of an Eel, and like that fish, the present species and its cousin to follow, are very tenacious, and will live for quite a long period out of their native element. In olden days a dish of Lampreys was considered a great delicacy, but to-day this interesting tenant of our rivers is mostly used as bait for other fishes.
Brook, or Planer's Lamprey.—Lampetra planeri (Fig. 30). The larval form of the Lamprey is known as the Pride. It has no teeth, but on the front of the mouth there is a fringe of barbules which serves the purpose of a sieve for sifting food. It resides in a tube, and although open at one end, the inhabitant works its way further in if danger threatens. This larval state of existence lasts for three or four years, and it is not until the creature has attained a length of several inches that the adult form is reached.
Planer's Lamprey does not grow to a greater length than 8 inches, and haunts smaller streams than Lampetra fluviatilis. Moreover, it restricts itself entirely to fresh water, and does not migrate to the sea. It is well distributed in our smaller waterways, and extends to Scotland, and is common in Ireland.
In general appearance this second species (there is a third species, the Sea Lamprey, Petromyzon marinus which enters fresh water to spawn, and is a much larger fish, attaining a maximum length of 36 inches), is dis-
