The True Sharks 541 



below. The heterocercal tail has no keel; the end is bent up- 

 ward; both dorsal fins are present, and the first is well in front 

 of the ventral fins; the last gill-opening over the base of the 

 pectoral, the head normally formed ; these sharks are ovovivipa- 

 rous, the young being hatched in a sort of uterus, with or 

 without placental attachment. 



Some of these sharks are small, blunt -toothed, and innocuous. 

 Others reach a very large size and are surpassed in voracity 

 only by the various Lamnida. 



The genera Cynias and Mustelus, comprising the soft-mouthed 

 or hound-sharks, have the teeth flat and paved, while well- 

 developed spiracles are present. These small, harmless sharks 

 abound on almost all coasts in warm regions, and are largely 

 used as food by those who do not object to the harsh odor of 



FIG. 334. Soup-fin Shark, Galeus zyopterus (Jordan & Gilbert). Monterey. 



shark's flesh. The best -known species is Cynias canis of the 

 Atlantic. By a regular gradation of intermediate forms, through 

 such genera as Rhinotriacis and Triakis with tricuspid teeth, we 

 reach the large sharp-toothed members of this family. Galeus (or 

 Galeorhinus) includes large sharks having spiracles, no pit at the 

 root of the tail, and with large, coarsely serrated teeth. One 

 species, the soup-fin shark (Galeus zyopterus), is found on the 

 coast of California, where its fins are highly valued by the 

 Chinese, selling at from one to two dollars for each set. The 

 delicate fin-rays are the part used, these dissolving into a finely 

 flavored gelatine. The liver of this and other species is used 

 in making a coarse oil, like that taken from the dogfish. Other 

 species of Galeus are found in other regions, Galeus galeus being 

 known in England as tope, Galeus japonicus abounding in Japan. 

 Galeocerdo differs mainly in having a pit at the root of the 

 tail. Its species, large, voracious, and tiger-spotted, are found 



