I05 



ELASMOBRANCHII. 

 PLAGIOSTOMATA. 



CARCHARIDAE. 



" Eye with a nictitating membrane. An anal fin ; two 

 dorsals." 



GALEOCERDO. 



Caudal fin with a double notch; mouth crescent shaped; 

 teeth subequal in both jaws, oblique, serrate on both margins. 



Galeocerdo falcatus, Ag. 



Corax fakatns, Poiss. Foss., t. iii., p. 226. 



This species is represented by a single tooth from the 

 cretaceous sandstone near the Garden of the Gods, Col. It 

 does not agree exactly with any descriptions or plates which 

 we have seen ; but the differences are probably owing to 

 the position or age of the specimen. The crowai is low, 

 broad, and not very acute, the edge is finely serrate, and 

 there is no sensible dift'erence between the serrations of the 

 two borders. The anterior border is undulating in outline, 

 but for the most part is convex ; the posterior is short and 

 straight, and sends out quite a long heel. One face of the 

 crown is flat and the other is strongly convex. The root is 

 stout and divided into two fangs, which are longer and more 

 distinct than is common in this species. There are no den- 

 ticles ; cementum smooth. 



Measurements. 



M. 



Length of crown -017 



Depth of fang -009 



Height of crown 'OH 



Galeocardo hartwellii, Cope. 



Cret. Vert, p.. 244. 

 This species belongs to the group G. Egcrtonii, Ag., having 

 the two edges subequal and symmetrical. A single tooth from 

 Cement Gulch, Col. 



