CENTRING. SCYLLIUM. 



143 



certainly does not belong to the Squatince, or even to 

 the same genus, strictly so termed, as Dr. Smith's 

 Rineodon; for the teeth are large, acute, and seem more 

 to resemble those of our Squalus ; both of the dorsal 



fins are placed behind the ventral ; the tail is long; the 

 caudal fin unequally and irregularly lobed : it only 

 agrees with Rineodon in its terminal mouth, and the 

 situation of the branchial openings, which appear very 

 large, and are all placed before the pectoral fin. Whe- 

 ther this singular fish naturally intervenes between the 

 Zyganince and Pristis, or whether it is the most aber- 

 rant type of the Squalince (in which case it would 

 represent Squatina and Rineodon), are questions which, 

 in the present confused state of this family, cannot be 

 determined. 



(124.) We now enter on the sub-family of Cen- 

 tring, or spiracled sharks, to which we are conducted, 

 as before observed, by the sub-genus Selachus, which has 

 the general structure of Lamna, with the spiracles suf- 

 ficiently large to become obvious, although, when com- 

 pared to the sharks now before us, they still remain 

 very small. 



(125.) The first genus we shall notice in the line 

 of affinity is Scyllium (S. canicula, fig. 16.), which, 



although agreeing with Lamna in its obtuse and pyra- 



