The True Sharks 533 



are small and mostly spotted, found in the warm seas. All 

 of them lay their eggs in large cases, oblong, and with long 

 filaments or strings at the comers. The cat-sharks, or rous- 

 settes, Scyliorhinus canicula and Catulus stellaris, abound in 

 the Mediterranean. Their skin is used as shagreen or sand- 

 paper in pohshing furniture. The species of swell-sharks 

 (Cephaloscylium) {C. uter, in California; C. ventriosus, in Chile; 

 C. laticeps, in Australia; C. umbratile, in Japan) are short, 

 wide-bodied sharks, which have the habit of filling the capacious 

 stomach with air, then floating belly upward like a globe-fish. 

 Other species are found in the depths of the sea. Scylio- 

 rhinus, Catulus, and numerous other genera are found fossil. 

 The earliest is Palcroscyllium, in the Jurassic, not very dif- 

 ferent from Scyliorhinus, but the fins are described as more 

 nearly like those of Giiiglymostoma. 



Close to the Scyliorhinidw is the Asiatic family, Hemi- 

 scylliidcB, which differs in being ovoviviparous, the young, 

 according to Mr. Edgar R. Waite, hatched within the body. 

 The general appearance is that of the ScyliorhinidcB, the body 

 being elongate. Cliiloscyllium is a well-known genus with sev- 

 eral species in the East Indies. Chiloscylliimi modestum is the 

 dogfish of the Australian fishermen. The Orectolobidw are thick- 

 set sharks, with large heads provided with fieshy fringes. Orec- 

 tolobus barbatus {Crossorhinus of authors) abounds from Japan 

 to Australia. 



Another family, Ginglymostomidce, differs mainly in the 

 form of the tail, which is long and bent abruptly upward at 

 its base. These large sharks, known as nurse-sharks, are found 

 in the warm seas. Ginglynwstoma cirrhatum is the common 

 species with Orectolobus. Stegostoma tigrinum, of the Indian 

 seas and north to Japan, one of several genera called tiger- 

 sharks, is remarkable for its handsome spotted coloration. 

 The extinct genus Pseudogaleus (voltai) is said to connect the 

 Scyliorhinoid with the Car chart old sharks. 



The Lamnoid or Mackerel Sharks. — The most active and most 

 ferocious of the sharks, as well as the largest and some of the 

 most sluggish, belong to a group of families known collectively 

 as Lamnoid, because of a general resemblance to the mackerel- 



