16 SELACHII : SQUALI. — IV. 
7. SPHYRNA Rafinesque. (An old name from odvpa, 
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 
nostrils. (Sphyrna.) 
9. S. zygeena (L.). HAMMER-HEADED SHARK. Width of 
«hammer ” twice its length. Gray. L.15 to 20 feet. All warm 
seas, N. to Cape Cod. (Eu.) (Anold name from ¢vyéy, a cross- 
beam.) 
bb. Head kidney-shaped, the frontal groove obsolete. (Reniceps, Gill.) 
10. S. tiburo (L.). Bonnet-Heap 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 Italian name of some 
shark.) 
Famity VII. GALHORHINIDA. (TuHE Typicat 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. 
b. 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. . . . . » » CARCHARHINUS, 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. . ScoLiopon, 11. 
8. GALEUS (Rafinesque) Leach. (JZustelus Cuvier.) 
(yadeds, shark; yadén, weasel.) 
a. Embryo not attached to uterus by a placenta; teeth very blunt. (Galeus.) 
11. G. canis (Mitchill). Dog SHarK. Hounp SHarx. Boca 
Dutce. 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. (£u.) 
9. GALEOCERDO Miller & Henle. (yaneés, shark ; 
Kepda, fox). 
12. G. maculatus (Ranzani). Tiger SHarx. Brown, with 
numerous large dark spots. L. 10 feet. Warm seas; rarely N. to 
N.Y. (Lat., spotted.) 
