198 DR. GIBBES' MONOGRAPH OF THE 



of the root of moderate size and approaching, the outer face near the point is plane, 

 lower down, and on the inner rounded, the edges near the point are alone cutting ; 

 the base of the cone cylindrical. I have seen but few specimens answering this 

 description, and the latter characters, the cutting edge and the cylindrical form of the 

 base are the only points in which it differs from Lamna elegans. 



Agassiz describes it as abundant in the Miocene of Europe. I do not know the 

 locality of the specimens I have, which are figured. 



I am lately indebted to Lieut. J. W. Abert of the Topographical Corps, United 

 States Army, for two specimens of teeth (Fig. 119, PI. xxvi.) from the Cretaceous 

 formation at Poblazon, in New Mexico. They are well marked specimens of Lamjia 

 contortidens, and are figured by him in his published report to the Secretary of War. 



7. L. {Odontaspis) hopei, Agassiz. Figs. 120, 121, 122, 123. — This is the broadest 

 of the subulate teeth, some are thick others more slender, all are nearly 

 cylindrical at the base, edges prominent and cutting towards the point, in proportion 

 as the tooth is flat, root thick and narrow. The nutritive canal is very perceptible 

 at the most prominent part of the inner face of the root. The lateral cones are 

 small and awl-shaped, often rudimentary, seldom preserved in large teeth. Outer 

 face flat near the point, insensibly rounded towards the base, where it is almost as 

 round as on the inner, compressed laterally, smooth, no trace of strisB. 



Found in the Eocene of South Carolina. 



8. L. {Odontaspis) verticalis, Agassiz. Figs. 124, 125, 126, 127. — Not as twisted 

 as L. Hopei, nor like L. compressa, because thicker : nor like L. elegans, because 

 there are no strife on the inner face. The prominent characters are straightness and 

 thickness at the base of the enamel, and of the root. The edges are cutting even to 

 the root. Lateral denticles are well marked, base of the enamel more sloped on the 

 outer than on the inner face ; the nutritive foramen distinct. 



My specimens are from the Eocene of South Carolina. 



9. L. {Odontaspis) gracilis, Agassiz. Figs. 128, 129, 130. — This is the most 

 slender of known fossil Lamnce, is very slender, has cutting edges the whole length, 

 outer face flat, inner sensibly swollen, no striae on inner face ; branches of root well 

 developed. I think L. suhulata, Agassiz, identical with this species. 



From the Eocene of South Carolina. 



Genus OTODUS, Agassiz. 



This is known only fossil. Agassiz has established it as intermediate between 

 Ozijrhina and Lamna and Carcharodon, but easily distinguishable from both. It 

 differs from Carcharodon by the entire absence of marginal dentelures, which are of 



