242 NORTH-CAROLINA GEOLOGICAL SURVEY. 



my memory in making the references to the genera to which 

 they belong. 



CARCHARODON. (Fig. 90.) 



NOTE. The annexed figure of a tooth, which may 

 probably be referred to this genus, is confined to 

 the eocene of Craven county. I have been unable 

 to refer it to a species already made known. 



SUB ORDER. THE RAYS. 



The rays are distinguished from sharks proper, by the flat- 

 ness of their bodies. There are several species in the sea 

 bordering the coast of ^Torth- Carolina, one of which is known 

 by the name of sting ray. The rays form three families: 1, 

 the pristides, familiarly known as the saw fishes, whose muz- 

 zles are elongated into a flat long extension, armed on each 

 margin by pointed teeth; 2, rajides, or rays, whose muzzle is 

 simple, but whose tails are not armed with a sting; 3, the 

 mylliobatides, comprehending those rays whose tails are 

 armed with a sting. The remains of the latter family are 

 known in the tertiary and cretaceous of North-Carolina. 

 Their teeth differ in form from those of the sharks, and would 

 scarcely be regarded as teeth at all, were it not for their oc- 

 currence in the living species upon the coast. They are 

 placed in the mouth in the form of a pavement, and occupy 

 the areas within the mouth of both jaws. They differ in form 

 from the pycnodonts in being angular. They are employed 

 in crushing hard bodies, as the shells of the inolusca. Their 

 mouths are placed below, and well situated for seizing the 

 animals upon which they feed. 

 ' 



FAMILY PRISTIDES. 



Fish which have a prolonged, bony muzzle, armed with a 

 plain horizontal series of teeth upon each margin. 



GENUS PRISTIS. (Fig. 93.) 



Single teeth broken from the flat plate near its junction 

 have been found in the superior layer of the eocene in Cra- 



