SQUALIDZ. — IV. 15 
ee. Last gill opening before base of pectoral; dorsal fins 
CaBCHAEUDS, 9. 
dd, Cauda! fin lunate, the lower lobe not munch shorter than the upper; 
tail with a kee! on each side, last gill opening before pectorals. 
hk. Gill openings rather large; teeth large. . . . . LaMsip2, 10. 
&k. Gill openings very large, nearly meeting both above and below; 
teeth small (largest of all fishes). . . - . CETORHISIDA, il. 
ga. Pectoral fins very large, wing-like, expanded at the base in front, this ex- 
pansion being separated from the neck by a deep notch; no anal fin. 
Squatmp, 12. 
Famiry IV. SQUALIDA), (Tue Doc-risues.) 
Sharks with two dorsal fins, each armed with a stout spine, and 
without anal fin; no nictitating membrane; spiracles moderate ; 
gill openings narrow, all before pectorals; ventral fins inserted 
posteriorly ; teeth small, compressed ; nostrils inferior, near front 
of snout. Genera 6; species about 15; small sharks, chiefly of the 
Atlantic. (Spinacide Auct.) 
a. Teeth in both jaws, simple, subquadrate, each with a nearly horizontal 
eutting edge, and a point directed outward; dorsal spines strong. 
Squares, 5. 
5. SQUALUS (Artedi) Linnzus. 
7. 8. acanthias L. Doc-risn. Dorsal spines not grooved; 
slate-color, back with whitish spots fading with age. L. 3 feet. 
North AtL, S. to Cuba; abundant N., its liver valued for the 
“Dog-fish oil.” (Eu.) (Gr. dxavOias, having spines.) 
Famiry V. SOMNIOSIDZ. (Tue Steerer Saarks.) 
Sharks with two dorsal fins, both without spine, and no anal fin, 
the first dorsal much before ventrals, otherwise essentially as in 
the Squalide. Genera 5; species 5 or 6, mostly large sharks of 
the Atlantic. 
a. Dorsal fins about equal; upper teeth lancet-shaped, incurved; lower quad- 
rate with a horizontal edge, ending in a point directed outwards; fins 
veryemall,, 2.5 6 EH Ree EG Sommiosts, 6. 
6. SOMNIOSUS Le Sueur. (Lat., sleepy.) 
8. 8. microcephalus (Bloch). SteEPer. Neerse. Color 
blackish; caudal blunt. L. 1% to 18 feet. Arctic seas, S. to Cape 
Cod. (Eu.) (pexpés, small; cepady, head.) 
Famity VI. SPHYRNIDA. (THe Hamuer-HEeapeD 
SHARKS.) 
Characters of the Galcorhinida, except that the head has a form 
hammer-shaped or kidney-shaped, its sides being much extended, 
the eyes borne at the ends of the hammer. One genus, with 4 or 
5 species; large sharks of the warm seas. 
