16 SELACHII : SQUALL IV. 



7. SPHYRNA Rafinesque. (An old name from a-cfjvpa, 

 hammer.) 



a. Teeth in both jaws oblique, each with a notch on the outside near the base ; 

 no spiracles. 

 b. Head truly hammer-shaped; a long groove extending forward from 

 jiostrils. (Sphyrna.) 



9. S. zygsena (L.). Hammer-headed Shark. "Width of 

 "hammer" twice its length. Gray. L. 15 to 20 feet. AU warm 

 seas, N. to Cape Cod. (£«.) (An old name from fuyo'K, a cross- 

 beam.) 



46. Head liidney-shaped, the frontal groove obsolete. {Eeniceps, Gill.) 



10. S. tiburo (L.). Bonnet-Head Shark. Width of " ham- 

 mer " not nearly twice its length. Ashy gray. L. 3 to 5 feet. 

 Warm seas, N. to Va. (Eu.) (Tiburo, an ItaUan name of some 

 shark.) 



Family VII. GALEORHINID^. (The Typical Sharks.) 



Sharks with two dorsals and an anal fin ; no spines ; tail mod- 

 erate, not lunate, bent upwards, the fin notched below near the 

 tip ; basal lobe short ; no caudal keel ; last gill opening above base 

 of pectoral ; eye with nictitating membrane ; head normally formed. 

 Genera 15, species about 60, found in all seas. 



a. Teeth blunt, paved, without cusps or cutting edges; spiracles present; 

 no pit at root of tail ; labial folds about mouth. . . . Galeus, 8. 

 aa. Teeth more or less compressed, with sharp cutting edges. 

 6. Spiracles present ; teeth large; serrated. 



c. Root of tail with a pit above; caudal fin with two notches. 



Galeocerdo, 9. 

 bb. Spiracles none; teeth sharp; a pit at root of tail. 



d. Teeth all serrate in the adult Carchakhdots 10. 



dd. Teeth all entire, all except the median ones oblique; their points 



turned away from the middle so that the inner margins are 

 nearly horizontal, and form a cutting edge. . Sooliodon, 11. 



8. GALETJS (Rafinesque) Leach. (Mustelus Cuvier.) 



(yaXeot, shark; yakl-q, weasel.) 



o. Embryo not attached to uterus by a placenta; teeth very blunt. (Galeus.) 



11. G. canis (Mitchill). Dog Shark. Hound Shark. Boca 

 DuLCE. First dorsal higher than long, its middle midway between 

 pectorals and ventrals; snout shortish. Pale gray. L. 3 feet. 

 Smallest of our sharks. N. Atl. ; common N. (Eu,) 



9. GALEOCERDO MuUer & Henle. (-yaXedr, shark ; 

 (tepScB, fox). 



12. G. maoulatus (Ranzani). Tiger Shark. Brown, with 

 numerous large dark spots. L. 10 feet. AVarm seas ; rarely N. to 

 N. Y. (Lat., spotted.) 



