The fishes of this genus are of small size, and commonly called “Dog-fishes.” They are coast fishes, living on the bottom, and feeding on Crustaceans, dead fishes, etc. None of the eight species known have a very wide distribution, but where they occur they are generally sufficiently abundant to prove troublesome to fishermen. They inhabit most parts of the temperate and tropical seas. On the British coasts two species are found, the “Larger” and “Lesser spotted Dog-fish,” _Scyllium canicula_ and _Scyllium catulus_, which are said to be more plentiful among the Orkney Islands than elsewhere. They are scarcely ever brought to market; but the fishermen of some localities do not disdain to eat them. Their flesh is remarkably white, a little fibrous, and dry. In the Orkneys they are skinned, split up, cleaned, and then spread out on the rocks to dry for home consumption. The skins are used for smoothing down cabinet-work. It would be worth while to apply the fins of these and other Sharks, which are so extensively used in China for making gelatine soups, to the same purpose in this country, or to dry them for exportation to the East. Most of the species of Dog-fishes are spotted, and those of the allied genera, _Parascyllium_ and _Chiloscyllium_, very handsomely ornamented. Closely allied to _Scyllium_ is _Pristiurus_, from the coasts of Europe, which is provided with a series of small flat spines on each side of the upper edge of the caudal fin. Fossil forms of Dog-fishes are not scarce in the Lias and Chalk: _Scylliodus_, _Palæoscyllium_, _Thyellina_, _Pristiurus_. GINGLYMOSTOMA.--The second dorsal fin opposite to, and somewhat in advance of, the anal. Eyes very small; spiracle minute and behind the eye. Nasal and buccal cavities confluent. The nasal valves of both sides form one quadrangular flap in front of the mouth, each being provided with a free cylindrical cirrhus. The fourth and fifth gill-openings are close together. The teeth stand either in many series, each having a strong median cusp and one or two smaller ones on each side (_Ginglymostoma_), or they stand in a few (three) series only, the foremost only being in function, and each tooth having a convex, finely and equally serrated margin (_Nebrius_). Four species from the tropical parts of the Atlantic and Indian Oceans, attaining to a length of some 12 feet. Pelagic.