V 



130 University of California Publications. [Geology 



Cranium. — The cranium had suffered considerably from 

 weathering previous to the discovery of the specimen, and lacks 

 all of the region anterior to P 2 and parts of both jugal arches. 

 Superiorly the forehead is broad and flat, slightly domed post- 

 eriorly along the line of the median suture. The temporal ridges 

 unite at about the anterior third of the length of the brain case to 

 form a sagittal crest, which does not rise above the frontal plane 

 and terminates posteriorly in a prominent triangular knob. The 

 brain case is somewhat flattened above and moderately con- 

 stricted back of the orbits. The lateral walls are well rounded. 

 Above each orbit is a small supraorbital foramen from which a 

 shallow groove extends anteriorly. 



The back of the skull is narrow above, where the supraoccipi- 

 tal forms the posterior border of the knob-like occipital crest. A 

 narrow median keel is present but fades out toward the upper 

 border of the foramen magnum. 



In the lower view (PL 14, fig. 2) the bullae are seen to be 

 small, resembling those of Leptomeryx. They are separated 

 from the basioccipital by a prominent outgrowth of the petrosal. 

 Anterior to the bullae, a large foramen appears to represent the 

 conjoined foramen rotundum and foramen ovale, but as the 

 skull is somewhat fractured in this region the confluence of the 

 two foramina can not be fully verified. A foramen of consider- 

 able size occupies the interval between the inner end of the post- 

 glenoid process and the bulla. The posterior palatine border has 

 been somewhat crushed and the outlines are slightly restored in 

 the figure. 



In the lateral aspect of the cranium (PI. 14, fig. 1) the orbits 

 are seen to be large and entirely enclosed. The frontal and jugal 

 processes overlap, but are not completely fused. The jugal bor- 

 der is more prominent than the frontal, indicating that the eye 

 faced upward. The lachrymal and anterior frontal borders of 

 the orbit are mammilated. A prelachrymal vacuity is present. 

 This portion of the skull has suffered from weathering and the 

 exact border of the vacuity is not well shown in the figure, but 

 the rounding of the unfractured free edges of the maxillary 

 and lachrymal may be seen with the aid of a lens. 



