SPINOUS SHARK. 



59 



flat above, and slightly sloping to the muzzle, which is 

 rounded ; nostrils transverse, and each partially divided by a 

 narrow membranous lobule, which projects backwards from its 

 anterior margin ; their position is nearly over the most pro- 

 jecting, or central portion of the upper jaw, considerably 

 nearer to the eyes than the tip of the snout, and about half 

 way between the latter, and the angle of the mouth. Eyes 

 rather nearer to a line raised from the angle of the mouth 

 than to the nostrils ; pupil circular and small ; postocular 

 spiracle scarcely visible. Gape wide and arched, having at 

 each corner a triangular fold of skin formed by the union of 

 the upper and lower lips. Teeth regularly placed upon each 

 jaw, only one row in use at a time, the rest reclined ; they 

 are large, compressed, and somewhat quadrangular, the cut- 

 ting edges nearly horizontal, and both of their sides are 

 generally bicuspidate, as will be seen by the figures here in- 

 serted, representing from both specimens the teeth of both 

 jaws as opposed to each other. 





Branchial openings all in front of pectoral fins ; the first not 

 more than half the length of the fifth. Pectoral fins rather 

 small, the hinder edges nearly square ; the dorsal fins are 

 small, the first narrower at its base than at its extremity, 

 which is slightly rounded ; the second nearly throughout of 

 equal breadth, the hinder edge almost square ; the ventral 

 fins short, broader behind than at their bases, and their pos- 

 terior edges slightly undulated ; the caudal fin entire, some- 



