BY SAMUEL GARMAN. 55 



the order making the current enter below and escape above. 

 In most Selachians this current is secured by means of the 

 nasal valve, which covers about half of each nostril. 



The teeth are constructed for grasping and from their 

 peculiar shape and sharpness it would seem as if nothing 

 that once came within their reach could escape them. 

 Even in the dead specimen the formidable three-pronged 

 teeth make the mouth a troublesome one to explore. 

 Points of teeth in perfect preservation, shape of the cusps, 

 and the structure of the small portion of the intestine left 

 by the captor, leave little room for doubt that the food of 

 the creature was such as possessed comparatively little 

 hardness in the way of the mail or other armature. 



No other shark of which we know has the opercular flap 

 free across the throat. In this particular it recalls the 

 fishes. There is a certain embryonic look about the spe- 

 cies, as others who have seen it also remark, that calls for 

 a comparison with fossil representatives of the Selachians. 

 Among them I have been unable to find anything which 

 might be considered at all near. InCladodus of the 

 Devonian there is a form with teeth somewhat similar, 

 a median and two lateral cones on each tooth, but 

 the cones are straight instead of curving backward, and 

 the enamel is grooved or folded instead of smooth. How- 

 ever, the type is one which produces the impression that 

 its affinities are to be looked for away back, probably ear- 

 lier than the Carboniferous, when there was less difference 

 between the sharks and the fishes. 



