CARCHAEINUS. 123 



Snout elongate, sharp, preoral length equal to six sevenths of the width of 

 the mouth; nostrils at two fifths of the distance from the mouth to the end, 

 nasal valve with a sharp lobe near the inner angle of the nostril. Diameter of 

 eyes greater than width of nostril. Teeth in 31 rows, cusps narrower, bases 

 broad, two rooted; upper little broader in the cusp, with denticulations at each 

 side on the basal process; lower more erect, smaller, without denticulations. 

 Length of pectoral equal the distance from the nostril, width equal five sevenths 

 of the length, fin pointed, subfalciform. First dorsal moderately pointed, origin 

 one fourth the length of the base farther back than the pectoral. Second dorsal 

 opposite the anal, hind border nearly straight, base not half the length of that 

 of the first dorsal; hind margin of anal indented, base like that of second dorsal. 

 Caudal about one fourth of the total length, more than twice the length of the 

 subcaudal lobe. 



The differences between the types of H. signatus and H . longirostris appar- 

 ently are no greater than those obtaining in individuals of the same species; at 

 the inner side of the bases of the teeth on the type of H. longirostris the 

 denticles are more distinct. 



Cuba. 



Carcharinus. 



Carcharinus Blainv., 1816, Bull. Soc. philom., p. 121 (part); 1830, Poiss. Fr., p. SS. 



Carcharias Ctrv., 1817, Reg. anim., 2, p. 125 (part; non Carcharias Raf., 1810). 



Prionodon Muller & Henle, 1841, Plagios., p. 35 (part). 



Eulamia Gill, 1861, Ann. N. Y. lye, 7, p. 401. 



Platypodon, Isogomphodon, Lamiopsh, Isoplagiodon Gill, 1861, ibid. 



Snout produced in front. Nostrils inferior, separated from the mouth and 

 from one another. Mouth inferior, curved forward, labial folds rudimentary 

 or short. Teeth compressed, subtriangular, with a single large sharp cusp. 

 Eyes with a well-developed nictitating membrane. No spiracles. First dorsal 

 generally the larger, opposite the space between the pectorals and the ventrals. 

 Tail with pits at the root of the caudal; vertebral axis of the caudal moderately 

 raised; subcaudal lobe produced. 



Numerous species have been found fossil in the Eocene and later forma- 

 tions. 



Second dorsal smaller than the anal, origin farther forward 

 snout short, broadly rounded, nostrils about mid length 



teeth serrated, upper broad, triangular, lower narrower 



pectorals f as broad as long, reaching little beyond dorsal origin 



/ilatyodon (page 126) 



