58 Annals of the Carnegie Museum. 



The mandible is long and slender with a high and thin coronoid 

 process and a well developed angle. Back of the canine, which forms 

 a closed series with the incisors, there is a long diastema. On the 

 left ramus is a small round alveolus for a single rooted P T , while the 

 corresponding tooth apparently had dropped out and the alveolus 

 almost closed on the right ramus of the jaw. The internal median 

 tubercles of the inferior cheek-teeth are separated by a narrow groove, 

 a character common to this genus. The cingula are well developed 

 on the external faces of the cheek-teeth, while internally they are not 

 nearly so well developed. Plate XIX is reproduced from carefully 

 made drawings and illustrates many points which are omitted in this 

 preliminary description. 



The pelvis is broken off anteriorly and posteriorly and is depressed 

 by vertical crushing ; it shows, however, that it is relatively shorter 

 antero-posteriorly and the anterior portion of the ilium is more rapidly 

 expanded than in Mesohippus. The acetabulum is deep, as is also 

 the pit for the round ligament. The pubis and ischium are quite 

 robust, and the pubic symphysis is relatively heavier than in Equus. 

 The obturator foramen is of considerable size and is subovate in 

 outline. 



The shaft of the femur is quite heavy and is nearly straight ; the 

 head is nearly sessile and has a deep narrow groove on the tibial 

 border for the round ligament. The great trochanter is prominent, 

 as are also the lesser and third trochanters. The distal end is charac- 

 terized by its great antero-posterior diameter. The internal ridge of 

 the rotular trochlea is much heavier than the external one, but is com- 

 paratively less highly developed than in Equus. The pit for the 

 plantar muscle is deeper than in the recent horse. 



The tibia is proportionally somewhat longer and slenderer than that 

 of Equus. The fossa on the posterior face near the proximal end is 

 deeper and is bounded by more prominent and sharper ridges laterally 

 than in the latter genus. The cnemial crest extends lower down on 

 the shaft of the bone and the internal malleolus of the distal end is 

 relatively less developed than in the recent horse. The cuboid facet 

 of the calcaneum is more oblique antero-posteriorly than that in Equus. 



Measurements. 



mm. 



Distance from occiput to and including incisors 370 



Distance from occiput to posterior border of orbit 157 



