416 



University of California. 



[Vol. 3. 



As the teeth wear, those of the superior series increase in 

 transverse diameter aud decrease anteroposteriorly. This is due 

 to the great obliquity of the inner crescents which slope from the 

 triturating surface toward the palate, and to the anterposterior 

 constriction of the long tooth crowns as the roots are approached. 

 In the last superior molar, the anterposterior diameter remains 

 more constant than in the other teeth, due to the posterior 

 prolongation of the metastyle which tends to increase in width 

 toward the alveolar margin. 



Affinities. — The closer affinities of Euceratlierium are not 

 clear. It may be placed in the sub-family Ovinae but can not 

 be regarded as intimately related to any existing North Ameri- 

 can member of that group. The cranium is larger than in the 

 bighorn sheep while the horn-cores are smaller, are situated 

 much farther behind the orbits, and differ greatly in form and 

 curvature. Although there is a resemblance to Ovibos in dental 

 structure, the horn-cores are of entirely different type. A rela- 

 tionship with the cattle is excluded by fundamental differences 

 in dental structure. Euceratlierium is separated from the goats 

 by the presence of a lachrymal pit. This character serves to 

 distinguish it from Haplocerus, from which it differs also in 

 greater size, in the shape and position of the horn-cores and in 

 the exclusion of the parietal from the cranial roof. 



As Euceratherium belongs to a comparatively late subdivision 

 of the Quaternary, it is probable that the genus will be found to 

 be represented elsewhere on the coast in some of the ossiferous 

 alluvial deposits unless it was restricted to mountainous regions 

 where its remains would stand little chance of being well pre- 

 served unless they were entombed in caves. It is not probable 

 that an animal of such size and weight was confined to the 

 higher summits like the sheep and goats, but rather, as the 

 specific name suggests, frequented the lower hills. Its absence 

 from the typical Quaternary plains faunas of California and 

 Oregon may be interpreted in favor of the latter view. 



