BY SAMUEL G ARM AN. 55 



the Order makingthe current enter belowaud escape above. 

 Tu most Selachiaiis this current is secured by means of the 

 nasal valve, wliich Covers about half of each nostril. 



The teeth are constructed for grasping and from their 

 peculiar shape aud sharpuess it would seem as if nothing 

 that ouce came withiu their reach could escape them. 

 Even in the dead speciineu the formidable three-pronged 

 teeth make the mouth a troublesome one to explore. 

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

 aud 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 knowhas the opercular Aap 

 free across the throat. In this particular it recalls the 

 fishcs. 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 

 mio:ht be cousidered at all near. In öladodus 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 back ward, and 

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

 ever, the type is one which produces the Impression that 

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

 lier than the Carbouiferous, when there was less difference 

 between the sharks and the fishes. 



