Cope.] 4;db [May 3, 



MM. 



r transverse 21.5 



Diameters of crown -< anteroposterior 21.5 



( longitudinal 450.0 



From Tehuichila, State of Vera Cruz, Mexico, on the borders of Hi- 

 dalgo ; from a bed of Loup Fork age. 



HiPPOTHERIUM PENINSULATUM Cope. 



Proceedings A.merican Philosophical Society, 1885, p. 150, Fig. 1. 



Ci'own of superior molar long, curved. Grinding face with anteropos- 

 terior diameter considerably exceeding the transverse. Internal column 

 large, its section a narrow anteroposterior oval, with both borders convex. 

 Internal enamel borders of internal crescents with a prominent loop at 

 junction, the posterior one with its posterior loop much smaller than the 

 column. A subquadrate area between the internal parts of the lakes is 

 connected by an enamel ridge with the anterior lake. Opposite and adja- 

 cent enamel borders of the lakes, with several close and deep plications, 

 which nearly cut off the adjacent horns. In like manner the posterior 

 horn of the posterior lake, and the anterior horn of the anterior lake are 

 almost cut off by the deep complex infoldihg of the anterior and posterior 

 borders respectively. The median and anterior external ribs of the crown 

 are well developed, and there is but little cement on the grooves. 



Measurements. M. 



Length of root, less crown 050 



T^. , o • -,■ r r anteroposterior 018 



Diameters of gnndmg face < ^ _ . _ 



^ " I transverse 015 



This superior molar tooth indicates a small species of the genus, and one 

 which is entirely typical in form. The plication of the enamel is greater 

 than any other species excepting the H. gracile. It resembles the H. ven- 

 ustum of Leidy, which is of similar dimensions. In that species the style 

 has a nearly circular section according to Leidy, which distinguishes it 

 satisfactorily. It approximates the H. montezumcB in the character of its 

 plications, but the oblong form, small size and greater curvature dis- 

 tinguish it. 



From the Loup Fork shales of Tehuichila, Vera Cruz. 



HiPPOTHERIUM sPECiosuM Leidy. 



Cope, Bulletin U. S. Geolog. Survey Terrs., No. 1, p. 12, Jan., 1874. Re- 

 port Expl. Surv. W, of lOOlh Meridian, Vol. iii, p. 322, PI. Ixxv, Fig. 



3, 1877. 



Hlppnrion speciosum Leidy. Proceed. Phila. Academy, 1858, p. 27 ; Ex- 

 tinct Mamm., Dakota and Nebraska, p. 282, PI. xviii. Figs. 6-19, 1869. 



