SQUALID^. CENTRININ^. 315 



Centrina Cuv. Form thick and heavy ; dorsal spines 

 strong, and placed in the fleshy part of the fins ; the 

 hinder dorsal opposite to the ventral fin ; cutting 

 teeth in the lower jaw placed in two rows ; those on 

 the upper narrow^ pointed_, and in several rows. 

 C. oxynotus Sw. Bloch, pi, 115. 



Spinax Cuv. General aspect of Mustelus ; spines placed 

 in front of the dorsal fins_, which are two ; jaws with 

 several rows of small cutting teeth, either the same 

 in both jaws, or those of the upper tricuspidate. 

 S. acanthias. Bloch, pi. 85. Yarr. ii. p. 400. 



Etmopterus Raf. Spiracles two, round ; muzzle pro- 

 duced; dorsal fins two, laciniated, and both armed 

 with a spine in front, the second nearly opposite to 

 the anal ; anal fin none ; tail unequal, oblique ; only 

 three branchial apertures ; teeth small, acute.* 

 E. aculeatus. Raf. Carat, p. 14. 



Scymnus Cuv. General structure of Centrina, but the 

 dorsal fins are without spines (thus representing 

 Scyllium); body smooth; upper teeth straight and 

 narrow. 



S. borealis Scoreshy. Yarrell, ii. 403. 



Centrophorus Muller and Henle. Resembling Spinax, 

 but the body covered with hard carinated scales or 

 prickles ; lower teeth indistinctly serrated; upper 

 teeth equilateral, and not serrated. 



Sq. squamosus Lac. spinosus Lac. 



Galeus Antiq. Raf. Dorsal fins two, destitute of spines; 

 anal fin present ; general form of Scymnus ; bran- 

 chial apertures five ; tail and caudal fin oblique ; 

 divisions unequal ; teeth serrated only on one side. 

 G. vulgaris. Bloch. pi. 118. Yarrell, ii. 390. 



Scyllium Cuv. (fig. 96.) General characters of Selachus, 

 with which it agrees, also, in the presence of very small 

 spiracles; but the caudal fin is elongated, oblique, 



* See Vol. I. p. 131. 



