136 



Annals of the Carnegie Museum. 



the deep excavation of this facet posteriorly, so characteristic of the 

 Oligocene Titanotheres. Unfortunately these features cannot here 

 be compared with Diplocerns as the lunar is wanting in the type of that 

 genus, but when compared with the Oligocene Titanotheres one notices 

 especially that the facets of the unciform and magnum are more 

 nearly subequal in width, and the posterior portion of the facet for 

 the unciform is excavated equally as much as the posterior portion of 

 the facet for the magnum. The cuneiform carries a proportionally 

 large facet for the pisiform and the bone is much higher than in 

 Titanotherium. The pisiform differs from that of Diploceras and the 

 horned titanotheres generally by being relatively heavier. The 

 trapezium is of considerably large size and carries three facets on the 

 ulnar angle; a large median surface for the trapezoid, and two smaller 



facets separated from the larger by well 

 defined ridges and articulating, one with 

 the scaphoid, and the other with Mc. II. 

 the dorso-palmar angle of the trapezoid 

 bears indication of coming in contact 

 with the lateral face of the posterior ele- 

 vated facet of the magnum, a condition 

 which is much more clearly revealed in 

 the Oligocene Titanotheres, where there 

 is a decided facet on the posterior su- 

 perior face.® With the exception of the 

 nearly vertical articular facet for the 

 unciform, the broader palmar hook, and 

 the greater height of the magnum, this 

 bone differs in comparatively slight de- 

 gree from the same bone in Titanotherium. 

 The magnum is wanting in the type 

 material of Diploceras. The unciform 

 presents its most noticeable difference from the Oligocene Titanotheres 

 in its greater height and in the proximal articulations. Although the 

 facets for the cuneiform and lunar are separated by a prominent 

 ridge, there is not found in Dolichorhinus that large hemispherical 

 tubercle, which separates the two facets in the unciform in Titano- 

 therium. 



^ In comparing the trapezoid of the paratype of Diploceras I find that it has a 

 larger facet in this region than is present in the type and is perhaps much better 

 developed in that genus than in Dolichorhinus. 



Fig. 7. Front view of manus 

 of Dolichorhinus longiceps (?), 

 No. 2865, 14 iiat. size. 



