314 CLASSIFICATION OF FISHES^ ETC. 



nearly half-Tvay round the neck ; spiracles either ob- 

 solete or very small. 

 S. masimus. Auct. Pennant, iii. pi. 16. Yarr. ii. 396. 



Lamna Cuv. Spiracles either wanting or very minnte ; 



snout pyramidical ; branchial apertures placed before 



the pectoral fins ; sides of the tail with a projecting 



cai'inated ridge ; teeth as in Squalus. 



L. cornubicus. Bloch, pi. 86. monensis Cuv. Yarr. ii. 387. 



Rhineodon Synith, ^'' General characters of Selachus_, 

 but with the mouth placed at the tip of the snout;" 

 spiracles wanting ; no type mentioned ; rank and 

 affinities uncertain. 



Tetroras Raf. " No spiracles ; dorsal fins two ; anal 

 one ; branchial apertures rather large, four on each 

 side ; " muzzle obtuse ; teeth in the form of a rasp, 

 without lateral lines ; a carinated appendage on each 

 side the tail. 



T. Angiova. Raf. Carat, p. 11. 



Heptranchias Raf. '^'' Dorsal fin one ; anal one ; bran- 

 chial apertures seven on each side; tail unequal, 

 oblique." Taken from Lacepede. 



H. cinereus (Squalus cinereus Lac.) 



Scoliodon ^NIull., Hen. " Differs from Squalus only by 

 the teeth being of the same shape in the upper and 

 lower jaw; viz. the points directed towards the comer 

 of the mouth, with a smooth edge and a truncated 

 protuberance, either smooth and indented, on the 

 exterior side of the base. (5 species.)" 



Leptocharias Smith. '' Xasal valve elongated into a 

 cirrus ; caudal dimple wanting ; lower lobe of the 

 caudal fin obsolete ; teeth numerous, with one or two 

 lateral denticles on each side^as in Scyllium. (1 sp.)" 



2. ScBFAM. CENTRININ^. 



Head furnished with spiracles behind the eyes ; dorsal 

 fins in the typical genera generally armed with spines. 

 Centrixa. Anal fin wanting; dorsal fins two, each 

 being generally armed with a strong spine. 



