18 SELACHII: SQUALL IV. 



FAMILY IX. CARCHARIID^S. (THE SAND SHARKS.) 



Body elongate, the snout sharp ; mouth wide, the teeth large, 

 long, narrow, entire, very sharp, most of the teeth with one or two 

 small cusps at base ; gill openings all in front of pectorals ; dorsals 

 small, similar to the anal ; tail as in Galeorhinidce ; no nictitating 

 membrane ; spiracles minute. One genus and 3 species ; rather 

 small sharks, of the Atlantic. 



13. CARCHARIAS Rafinesque. (Odontaspis Agassiz.) 

 , jagged.) 



a. First and fourth teeth of the upper jaw, and first tooth of the lower without 

 basal cusps. (Euyomphodus Gill.) 



18. C. littoralis (Mitchill). SAND SHARK. Pectoral short. 

 Color gray. L. 6 feet. Cape Cod to S. C., rather common N. A 

 voracious little shark. (Lat., of the shore.) 



FAMILY X. LAMNID^E. (THE PORBEAGLES.) 



Body robust, contracted to a rather slender tail, which has a 

 keel on each side ; caudal fin lunate, the lower lobe nearly as large 

 as the upper, and not very different in form ; teeth large ; gill 

 openings wide, all in front of pectorals ; first dorsal and pectorals 

 large ; second dorsal and anal very small ; a pit at root of caudal ; 

 spiracles obsolete. Large, voracious sharks of the warm seas. 

 Genera 3, species about 6. 



a. Teeth slender, sharp, with entire edges; tail very slender. 



b. Teeth very slender, flexuous, without basal cusps . . . ISURUS, 14. 

 bb. Teeth broader, most of them with a small cusp on each side at base. 



LAMNA, 15. 



aa. Teeth broad, compressed, triangular, distinctly serrate; tail rather stout. 



CARCHARODON, 16. 



14. ISURUS Rafinesque. (to-oj, equal ; ovpd, tail.) 



a. First dorsal entirely behind pectorals, nearly midway between base of P. 

 and V. (Isuropsis, Gill.) 



19. I. dekayi (Gill). MACKEREL SHARK. Color bluish. 

 L. 15 feet. W. I., rarely N. (For James E. Dekay, author of the 

 Fauna of New York.) 



15. LAMNA Cuvier. (Aa/zra, a kind of shark.) 



20. L. cornubica (Gmelin). PORBEAGLE. MACKEREL SHARK. 

 First dorsal close behind pectorals ; snout conical, sharp ; back 

 elevated ; third tooth on each side in upper jaw small. L. 8 feet. 

 Warm seas, frequently N. to Cape Cod. (.) (Lat., pertaining 

 to Cornwall.) 



