SQUALID^. SQUALINiE. 313 



Alopias Raf. Spiracles none ; dorsal fins two^ the 

 posterior adipose ; tail and caudal fin very long^ un- 

 equally and obliquely divided ; the former as long as 

 the body; muzzle rounded ; teeth flat;, minute^ and 

 acute. 

 A. macrourus. Raf. Carat, vulpis Sw. Yarr. ii. 379. 



Cerictius Raf. " Spiracles wanting ; dorsal fins two, 

 the posterior much the largest, and bilobed ; branchial 

 apertures five on each side ; head with two bony 

 appendages in the form of horns." 



C. macrourus. E-af. Carat. 



Dalatias Raf. " Spiracles none ; dorsal fins two, 

 furnished with anterior spines ; anal fin wanting ; 

 tail unequally and obliquely lobed ; teeth unequal, 

 acute, disposed in different directions ; mouth ismall _; 

 eyes round ; branchial apertures five, narrow j " 

 head with numerous minute pores* scattered on both 

 sides j skin finely tuberculated. \ 



D. nocturnus. Raf. Carat.* pi. 11. 



Selachus. Caudal fin large, lunated, the lobes nearly 

 or quite equal ; teeth conic, acute, entire. 



Isurus Raf. No spiracles ; dorsal fins two, the pos- 

 terior adipose ; anal fin one, adipose ; tail large, 

 vertical, equally divided, and lunate ; snout very acute ; 

 base, or end, of the tail angiilated, and nearly winged 

 on each side ; branchial apertures very long and nar- 

 row ; each jaw has three rows of teeth near the pa- 

 late ; eyes small and round j hinder dorsal opposite 

 the anal fin. 



I. oxyrynchus Raf. 



Selachus Cuv. Teeth small ; snout short, obtuse ; 

 branchial apertures remarkably large ; extending 



* See also Vol. I. p. 129. The other species of Dalatias, described by 

 Rafinesque, is his D. sparaphagus, differing in having no spines to the dor- 

 sals ; its teeth are flat, long, acute, the lower in one row, and the upper 

 in two, these latter being the smallest. 



