The last mentioned are interesting little fishes that may be found on stony beaches at low tide, for they often remain under cover between the tide-marks, and may be seen on turning over stones and weeds. Perhaps the commonest of them is the Five-bearded Rockling (_M. mustela_), which has four barbels on the upper lip and one on the lower. It is of a dark-brown colour above, and light below, and makes nests of corallines in rock cavities. The Three-bearded Rockling (_M. tricirrhata_), known also as the Sea Loach and the Whistle-fish, is a larger species, sometimes reaching a length of a foot or more. Its colour is light brown, marked with darker spots, and, like the other species, it lives in the shallow water of rocky and weedy places. Another species--the Four-bearded Rockling (_M. cimbria_), known by the three barbels on the upper lip and one on the lower, is about eight inches long when full grown, and is found principally on the northern shores. Our next family (_Syngnathidæ_) contains some peculiar creatures called Pipe-fishes because their jaws are united into a tube. They have long and slender bodies that are covered with bony plates which form a kind of coat of mail and give them an angular form. They have very small gill-openings, a single dorsal fin, and no pelvics. Pipe-fishes are very sluggish in habit, swimming but little, and living in the shelter of weeds and stones on rocky coasts. In fact, they are not adapted for swimming, and their attempts at this mode of locomotion are awkward in the extreme, for their bodies are rigid and the tail very small. When removed from their hiding-places they move but little, and look as much like pieces of brown or greenish wood as fishes; and their rigid bodies are so completely encased in the bony plates that they alter but little in appearance when dried, and consequently the dried specimens are often seen in museum collections. All the British species, four in number, are small fishes, inhabiting the shallow water of rocky shores, and are often found hiding under stones near low-water mark. The largest is the great Pipe-fish or Needle-fish (_Syngnathus acus_), which grows to a length of about fifteen inches; and the smallest is the Worm Pipe-fish (_S. lumbriciformis_), which is of an olive-green colour, and has a short, upturned snout. The Lesser Pipe-fish (_S. typhle_), also known as the Deep-nosed Pipe-fish, is very abundant on nearly all rocky coasts, and may be distinguished from the others by having the ridge on the tail continuous with the lateral line and not with the dorsal angle. The other species is the Slender-nosed Pipe-fish or Snake Pipe-fish (_Nerophis ophidium_), the body of which is extremely slender, and the tail long and narrow. The male is provided with a series of small, cup-like cells, in each of which he carries an egg.