1884.] * [Cope. 



This specimen also agrees with those in the Mexican museums in the small 

 number of crests on the last inferior molar : four with a short rudimental 

 heel. Another specimen of apparently the same species is described and 

 figured by Leidy as having been brought from Tambla, Honduras.* This 

 tooth is apparently anomalous in the contraction of the third cross-crest. 



The range of this species may then be given as extending from Califor- 

 nia to the valley of Mexico, inclusive. 



A species apparently allied to the Dibelodon shepardi is the Mastodon 

 serridens Cope.f of which the typical specimen was brought from south- 

 western Texas. Premolar teeth of the same type were shown me by 

 Professor Castillo, in the museum of the School of Mines. These came 

 from a lignitic bed at Tehuichila, in the State of Morelos, of Loup Fork 

 age. This epoch is indicated by the presence of the genera Protohippus 

 and Hippotherium. The sharp, serrate edges of the crests distinguish the 

 molar teeth from those of the D. shepardi, and as the species probably 

 came from different horizons, they are probably distinct. A premolar 

 mingled with those of D. shepardi, from the valley of Toluca, much re- 

 sembles that of the M. serridens. 



Dibelodox tropicus Cope, sp. nov. 



Mastodon hurnboldtii? VonMeyer Palseontographica, 1867, Studien 

 ueber das genus Mastodon, p. 64, PL vi. Mastodon andium Leidy, Pro- 

 ceedings Academy Philada., 1876, p. 38. 



A second species of Dibelodon inhabited the valley of Mexico, of larger 

 size than the D. shepardi, and differing somewhat in the dentition. Von 

 Meyer describes and figures a ramus of a lower jaw, 1. c, brought by Herr 

 Uhde from Mexico, which has, according to Von Meyer, no mandibular 

 tusk, and probably a short elephantine symphysis. A very similar ramus, 

 containing the last molar tooth, was presented to the Philadelphia Acad- 

 emy of Natural Sciences by Dr. Isaac Coates, who obtained it from Tarra- 

 pota, on the Huallaga river, in Eastern Peru. The extremity of the 

 symphysis of this specimen is broken away, but enough remains to show 

 that it was probably short, and that there was no inferior incisor. 



Keference to Von Meyer's figure shows that the last inferior molar has 

 five well-developed cross-crests and a heel. The Peruvian specimen has 

 the same character, the fifth cross-crest a very little more contracted than 

 in Von Meyer's plate. Dr. Leidy describes the specimen as having four 

 transverse ridges, besides a strong tubercular talon. But it seems to me 

 that the talon is of such size as to be properly included in the cross-crests. 

 On the same principle one might say that the D. shepardi has three cross- 

 crests and a strong talon, as it has one less cross-crest than the D. tropicus. 

 The additional cross-crest, and the superior size, distinguish this form as a 

 species from the D. shepardi. Von Meyer perceived these differences, 

 and referred his specimen to the D. hurnboldtii. I am fortunately able to 



* Extinct Mammalia Dakota and Nebraska, PI. xxvii, fig. 14. 

 f American Naturalist, 1884, p. 524. 



