430 University of California Publications in Geology [Vol. 7 



of the crochet, and in its small size. The Mohave form seems to 

 be distinguished from Anchitherium by relatively smaller size of 

 the protocone and absence of internal cingulum. 



Lower Cheek-teeth. — The lower jaw specimen, no. 19764, (figs. 

 5a and 56) represents a form which in size is near Miohippus. 

 The cheek-teeth are braehyodont, without evidence of cement 

 covering. The crowns of the molars and premolars are slightly 

 rugose, and tend to be somewhat higher than in the average 

 Hypohippus. 



Figs. 5a and 5b. Parahippus( ?) ■mourningi. n. sp. P 3 to M 2 . No. 19764, 

 natural size. Fig. 5a, occlusal view; fig. 5b, outer side. Mohave Miocene, 

 Barstow Syneline, Mohave Desert, California. 



P 4 is considerably larger than M 1 in both anteroposterior and 

 transverse diameter. The metaconid and metastylid show a 

 distinct tendency to separate at the summit, the separation being 

 more marked than in typical Hypohippus, and less advanced 

 than in typical Parahippus. The entostylid is well developed. 

 The cingulum is well shown on the anterior and posterior sides 

 of the crown, but shows no distinct shelf on the outer and inner 

 sides. 



This specimen represents an anchitheriine horse smaller than 

 any known to the writer from post-Oligocene horizons, excepting 

 Arehaeohippus. It is in some respects intermediate between 

 Hypohippus and Parahippus. As Arehaeohippus also represents 

 a small form more advanced than Hypohippus and less advanced 



