16 SELACHII : SQUALL — IV. 



7. SPHYRNA Rafinesque. (An old name from acf>ipa, 



hammer.} 



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

 no spirai 

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

 nostrils. (Sphyrna.) 



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

 ■'hammer " twice its length. Gray. L. 15 to 20 feet. All warm 



. N. to Cape Cod. (-£«.) (An old name from (vyop, a cross- 

 beam.) 

 bb. Head kidney-shaped, the frontal groove obsolete. (Reniceps, Gill.) 



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

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

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



shark.) 



Family VII. GALEORHINID-ffi. (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. 



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

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

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

 b. Spiracles present; teeth large; serrated, 

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



(taleocerdo, 9. 

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



(/. Teeth all serrate in the adult Carchariiixus, 10. 



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



turned away from the middle so that the inner margins are 

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



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



(yaAeos, shark; ya\er}, weasel.) 



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



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

 Dulce. First dorsal higher than loner, its middle midway between 

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

 Smallest of our sharks. N. Atl.; common X. (£"«.) 



9. GALEOCERDO Midler & Ilenle. (ya\(6s, shark ; 



KfpSco, fox). 



12. G. maculatus (Hanzani). Tiger Shark. Brown, with 

 numerous large dark spots. L. 10 feet. Warm seas : rarely X. to 

 N. V. (Lat., spotted.) 



