40 LIST OF FISH. 



9. Heterodontina. — Last gill-slit over the pectoral; second 

 dorsal between the ventral and anal ; dorsals spinous. 



b. Anal distinct ; dorsal-fin one. 



10. Hexanciiina. 



c. Anal none ; dorsal-fins two. 



11. Acantiana. — Dorsal-fins with a spine in front. 



12. Dalatiana. — Dorsal-fins spineless. 



1. Nictitating membrane distinct; dorsal-fins hvo, first between 

 the pectoral and ventral ; anal distinct. ; front branchial-slits before 

 the front edge of the pectoral-fins. 



Squali (§ 2), Mull. &r Henle, Mag. Nat. Hist. ii. 1838. Plagiost. 



A. Spiracles none ; second dorsal-fin over the anal. 

 Squali (§ 2, a.), Mull. $■ Henle, Plug. 



Tribe 1. SQUALI ANA. 



The head is flat. The snout pointed, blunt or elongate sideways. 

 The nostrils have for the most part a small, three-sided flap to their 

 upper border. The eyelids enclose an acute, oval, or roundish 

 opening; the pupil is perpendicularly oval. The mouth is boldly 

 convex ; the corner fold of the mouth small. The teeth in this 

 family are generally three-cornered, flat, with the cutting-edge 

 entire or serrated, even-sided or unequal. The anal stands directly 

 opposite the second back-fin, or close before it or behind it. The 

 tail has always a short under lobe, and a slit in its under edge be- 

 fore the obliquely truncated end of the upper lobe. A small three- 

 cornered pit may be generally found on tbe upper and under sides 

 of the root of the tail. The intestinal valve is rolled lengthways, not 

 straightways. The scales are small ; the skin smooth. 



Carcharia?, Mull. $• Henle, Plag. 



Squalini, Bunap. Selach. Tab. Anal. 10, 1838. 



