126 



University of California Publications. 



[Geology 



PEROMYSCUS PARVUS, n. Sp. 

 PI. 14, Figs. 4 and 5. 



Type. — Portions of maxillary and mandible, No. 84, Univ. of Cal. Palae- 

 ont. Coll. 



Locality. — Upper Diceratheriurn beds, Middle John Day. Turtle Cove, 

 Giant Co., Oregon. 



Smaller than P. nematodon. Upper molars with two princi- 

 pal and two subsidiary enamel inflections on the outer side of the 

 tooth crown. 



The first two molars of the superior series are pre- 

 served in a fragment of the left maxillary. They are low 

 crowned and tuberculate. The subsidiary enamel inflections are 

 situated respectively anterior and posterior to the two principal 

 externa] enamel loops, and would disappear were the teeth 

 slightly more worn. In M x there is one wide external and two 

 narrower internal enamel invaginations. The second and third 

 lower molars are represented by the roots only. The lower in- 

 cisor is delicately grooved on the outer face. 



Type. — Cranium and mandible, No. 649, Univ. of Cal. Palaeont. Coll. 

 Locality. — Promerycoehoerus beds, Upper John Day. Haystack Valley, 

 Wheeler Co., Oregon. 



Rostrum long and broad. Interorbital region concave. Super- 

 ciliary ridges strongly developed, with abrupt posterior termina- 

 tion. Temporal ridges low, converging from the posterior ex- 

 tremities of the superciliary borders to form a prominent sagittal 

 crest. Mandibular symphysis with long straight superior border 

 separated from P 4 by a short concavity. Size large. 



E. sperryi may be distinguished from E. planifrons by the 

 flat forehead and absence of temporal ridges in the latter species. 

 In E. lambdoideus "there is no ridge-like thickening of the 



Measurements. 



Length M 1 to M 2 inclusive 



Length Mi to M ;l inclusive, on alveolar border 



Length M x antero-posteriorly 



Depth of ramus below Mj 



3.5 mm 



4 



1.5 

 3.3 



ENTOPTYCHUS SPERRYI, n. Sp. 

 PI. 14, Figs. 6 and 7. 



