190 The True Sharks 
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 corners. The cat-sharks, or rous- 
settes, Scylliorhinus canicula and Catulus stellaris, abound in 
the Mediterranean. Their skin is used as shagreen or sand- 
paper in polishing furniture. The species of swell-sharks 
(Cephaloscylium) (C. uter, in California; C. ventriosus, in Chile; 
C. laticeps, in Australia; C. wmbratile, 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. Scyllio- 
rhinus, Catulus, and numerous other genera are found fossil. 
The earliest is Paweoscyllium, in the Jurassic, not very dif- 
ferent from Scylliorhinus, but the fins are described as more 
nearly like those of Ginglymostoma. 
Close to the Scylliorhinide is the Asiatic family, Hemi- 
scyllide, which differs in being ovoviviparous, the young, 
according to Mr. Edgar R. Waite, hatched within the body. 
The general appearance is that of the Scylliorhinide, the body 
being elongate. Chiloscyllium is a well-known genus with sev- 
eral species in the East Indies. Chiloscyllium modestum is the 
dogfish of the Australian fishermen. The Orectolobide are thick- 
set sharks, with large heads provided with fleshy fringes. -Orec- 
tolobus barbatus (Crossorhinus of authors) abounds from Japan 
to Australia. 
Another family, Ginglymostomide, 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. Ginglymostoma 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 
Scylliorhinide with the Carchariotd 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- 
