62 GEOLOGICAL SURVEY OF TEXAS. 



cies occupies an intermediate position in structure, as it does in time, be- 

 tween the M. (JDihelodon) mirfficus and the D. humholdUi. The occur- 

 rence of the latter species in Texas indicates a great range in latitude, 

 since its remains have been found hitherto principally in Buenos Ayres 

 and Chili. Its supposed occurrence in Mexico I have shown to be based 

 on a misapprehension.* 



A specimen found not far from Pernambuco, Brazil, has, however, been 

 recently presented to the Academy of Natural Sciences of Philadelphia 

 by Dr. J. Cheston Morris, and this discovery shows that a tropical cli- 

 mate has been no obstacle to the migration of the species. The specimen 

 referred to includes three crests of the last true molar, which is charac- 

 teristic. 



PVom its geological position, I suspect that the Mastodon mirificus, 

 Leidy, will turn out to be a Dibelodon. 



DIBELODON TROl'IOUS, Cope. 



Plates XV, Figure 1; XVI, Figures 1-3. 



Proceedings American Philos. Soc. 1884, p. 7. 



Mastodon sp.. Cope, loc. cit., 1892, 123, 123. 



Mastodon humboldtii?, Cuv. Von Meyer Paleontographica, 1867, Stu- 

 dien neb. Mastodon, p. 64, PI. VI. 



Mastodon successor, Cope, Proceed. Academy Philadelphia, 1892, p. 227. 



A few yards distant from the locality in which I found the superior 

 molar teeth of the Dibelodon humboldtii, the head of a humerus projected 

 above the surface of the ground. Following the shaft downwards, I 

 reached a large tusk, which was lying in contact with its inferior third. 

 On fully exposing the tusk, I found that it was resting upon a mandible 

 with complete symphysis and two molar teeth on each side, but lacking 

 angles and condyles. At various other points on the same hill I observed 

 fragments of teeth and bones of mastodons. Besides this specimen, Mr. 

 W. F. Cummins found near Mount Blanco a last premolar of two other 

 individuals, and a last premolar from the Paloduro Canyon. It was from 

 the teeth found by Mr. Cummins that the first indication of this species 

 in the Blanco bed was obtained, as above cited. 



The portion of tusk exposed is about four feet of the basal region. 

 This did not display any enamel band, but its absence from this part of 

 the length does not disprove its presence on the more distal region. The 

 question of its presence or absence must be left in doubt for the present. 

 The symphysis is short and is without incisors. It is nearly as short as 

 in the elephants, and is much more contracted than in the D. cordiller- 

 arum. The constitution of the molar tubercles is as in that species, and 



♦Proceedings American Philosophical Society, 1884, p. 7. 



