168 0. C. Marsh — Principal Characters of the Dinocerata. 



and the ischium has less posterior extension than in the ele- 

 phant. The thyroid foramen is an elongate oval. The femur 

 is proportionally about one-third shorter than that of the ele- 

 phant. The head of this bone has no pit for the round liga- 

 ment, and the great trochanter is flattened and recurved 

 There is no indication of a third trochanter. The distal end oi 

 the femur is more flattened transversely than in the elephant, 

 and the condyles are more nearly of the same size. The cor 

 responding articular faces of the tibia are consequently aboul 

 equal, and also contiguous, with no prominent elevation be- 

 tween them. When the limb was at rest, the femur and tibia 

 were nearly in the same line, as in the elephant and man. The 

 patella is elongate, and oval in outline. The fibula is slender, 

 and entire, with articular faces well marked at each extremity. 

 The astragalus has no distinct superior groove. Its anterioi 

 portion has articular faces for both the navicular and cuboid, 

 thus differing from Proboscidians, and agreeing with Peris- 

 sodactyls. The calcaneura is very short, its longitudinal and 



transverse diameters being about equal. It does not articulate 

 with the navicular, as in Elephas^ and has only a small face for 

 the cuboid. There are four well developed digits in the pes, 



1 rudimentary or small hallux. The i 



shorter than the metacarpals. The phalanges and sesamoid 

 bones are smaller, but otherwise similar to those of the manus. 

 The hind foot is shown in figure 1 of Plate VI. None of the 

 bones of the skeleton are hollow 



The known species of Dinoceras nearly equalled the elephant 

 in size, but the limbs were shorter. The head could reach the 

 ground, and there is no evidence of a proboscis. All the 

 remains of the genus yet discovered are from the Eocene of 

 Wyoming. 

 Yale CoDege, New Haven, Jan. 18th, \%*l&. 



(To be continued.) 



Explanation of PLATEa 



w. One-eighth natural size. 



Plate m..— Dinoceras mirabile. Superi 



Plate lY .—Dinoceras mirabile. Cast of brain cavity. Figure 1, side v 

 2, top view; figure 3, bottom view. One-half natural sii 



Plate V. — Dinoceras laticeps Marsh. Lower jaw. Figure 1, front v: 

 2, Bide view ; figure 3, top view. One-fifth natural size. 



Plate Yl.— Dinoceras. Figure 1, hind foot; figure 2, fore foot. One-tl 



