1. CARCHAEIAS. 351 



Fam. 1. CARCHARIID.E. 



The first dorsal fin opposite to the space between 

 pectoral and v^entral fins, without spine ; an anal fin. 

 Eye with a nictitating membrane. Mouth crescent- 

 shaped, inferior. 



Group A. CARCHARIINA. 



1. C ARCH ARIAS. 



Carcharias, Cuv., Midi, i^- Ilenle. 



The first dorsal fia oi^positc to the space between pectorals and 

 ventrals, without spine. A pit at the root of the caudal, which has 

 a distinct lower lobe. Membrana nictitaus present. 8piracles none. 

 Mouth crcscent-shajied ; the labial groove or fold is confined to, or 

 does not extend much beyond, the angle of the mouth. Snout pro- 

 duced longitudinally. Teeth with a single sharp cusp, more or less 

 diluted and triangular. 



Seas of the temperate and tropical regions. 



The number of species of true Sharks has been unduly multiplied; 

 and therefore their determination has become a matter of some diffi- 

 culty. Muller and Henle have distinguished the following sub- 

 genera: — 



A. None of the teeth denticulated *. 



a. The upper and lower teeth oblique, not swollen at the base. 



a. ScuUodun, p. 357. 

 h. The lower teeth swollen at the base, points slender. 



ii. rhtjsodon, p. 360. 

 c. The lower teeth erect y. AprionoUi/n, p. 3(51. 



B. Some or all the teeth denticulated. 



a. Only the base of the upper teeth with denticulatious. 



S. Hypoprion, p. 362. 



b. The base as well as the cusp of some or of all the teeth serrated. 



f . Prionodon, p. 303. 



1. ScOLIODONt. 



Scoliodon, Mull, ^- Henle. 

 Carcharias with oblique fiat teeth in both jaws, tvithout any scrra- 



tlU'C. 



* It must be remarked that in the young of at least some of the species of 

 Prionudon the teeth are not serrated, and. that such examples may be taken for 

 Scoliodon. 



t 1. Sqrialus porosus, Poc//,Mc>n. Cuba, ii. p. 339, pi. 19. figs. 11, 12(tceth'l. — 

 Cuba. 



