301 



tooth represented in Fig. 5, Plate XXXVII, magnified 1£ diameters. The 

 specimen was obtained from the yellow limestone of the Cretaceous series, 

 near Vincentown, Burlington County, New Jersey, and it belongs to the 

 Museum of the Academy. The crown of the tooth is 7| lines by 2| lines. 

 The extremities are angular; the sides nearly straight or in the feeblest 

 degree sigmoid. The upper surface is convex; and its median ridge is almost 

 obsolete. The secondary ridges, proceeding transversely from the former, 

 become branched and finely reticulated at the boundaries of the crown. 

 The groove on the inner side of the latter, for co-adaptation to the contig- 

 uous tooth, is about three-fourths of a line in width. The fang or con- 

 tracted base of the tooth is about half the breadth of the crown. 



Professor Emmons has represented the tooth of an Acrodus in Fig. 97 of 

 his Report of the North Carolina Geological Survey for 1858, which he attrib- 

 utes to the Miocene Tertiary. If it really pertains to this formation, it indi- 

 cates the latest known species of the genus. The species has been named 

 Acrodus Emmonsi 



GALEOCERDO. 



GALEOCEEDO FALCATUS. 



The teeth of Galeocerdo are nearly as broad as they are long, and the root 

 is but moderately notched. The anterior border of the crown is strongly 

 arched and oblique ; the posterior border is slightly curved and nearly verti- 

 cal, but is abruptly prolonged backward at its base. The borders of the 

 crown are serrated ; the point is 'somewhat acuminate. 



Teeth from the chalk formations of Europe figured in the " Poissons Fos- 

 siles," and ascribed by its illustrious author to half a dozen different species, 

 are, with reason, by Reuss referred to a single one with the name of Corax 

 heterodon. As Agassiz, according to Gibbes, does not now consider Corax 

 different from Galeocerdo, I have used this name, together with the earlier 

 specific one of falcatus, to represent the Corax heterodon of Reuss. 



Many specimens of well-preserved teeth, submitted to my examination, 

 from various localities of the American Cretaceous formation, appear to belong 

 to Galeocerdo falcatus. The variations in the form and size of different teeth 

 I think are sufficiently accounted for from the difference of position the teeth 

 occupied in the jaws and upon difference in age. 



Figs. 29 to 31, Plate XVIII, represent three of these teeth, obtained with 



