326 FISHES. 



remarkably white, a little fibrous, and dry. In tbe 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, Palceoscyllium, Thyellina, Pristiurus. 



GiNGLTMosTOMA. — 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 (Oingly- 

 mostoma), or they stand in a few (three) series only, the fore- 

 most only being in function, and each tooth having a convex, 

 finely and equally serrated margin [Nebnus). 



Four species from the tropical parts of the Atlantic and 

 Indian Oceans, attaining to a length of some 12 feet. 

 Pelagic. 



Stegostoma. — The first dorsal above the ventrals, the second 

 in advance of the anal, which is very close to the caudal. Tail, 

 with the caudal fin, exceedingly long, measuring one-half of the 

 total length. Eyes very small, spiracle as wide as, and situated 

 behind, the orbit. Nasal and buccal cavities confluent. Snout 

 very obtuse ; upper lip very thick, like a pad, bent downwards 



