292 DAVIDSON BLACK 



The olfactory bulbs are large, pedunculated and project a 

 considerable distance rostrad of the hemispheres. On their dor- 

 sal surfaces they show peculiar and characteristic markings again 

 recalling the condition obtaining in Orycteropus (vide supra). 



Moodie (1. c, p. 135) states that there are no sacculations to 

 be observed in the frontal sinuses of Merycochoerus, an oreo- 

 dont of Miocene and lower Pliocene age. This author has, how- 

 ever, noted the possibility of a greater development of the frontal 

 sinuses and presence of sacculations in other and more ancient 

 oreodonts. Certainly the peculiar markings upon the dorsal 

 surface of the olfactory bulbs in Specimen IV would suggest the 

 presence of olfactory terminations in the dorsally placed frontal 

 sinuses of Merycoidodon such as obtain in certain modern macros- 

 matic carnivores and edentates. 



Cerebellum. The essential details of cerebellar structure are 

 preserved to a large extent on this portion of the cast. This 

 cast is apparently from an animal not completely mature in its 

 development as evidenced by the large vacuities of the parieto- 

 temporal and associated channels as well as by the spongy nature 

 of the endocranial surface over the upper part of the lobulus medi- 

 anus posterior. This evidence is borne out by the fact that many 

 of the cranial sutures are not obliterated and the tentorial 

 groove is shallow and wide. Judging from the measurements 

 this cast is from a young but full grown adult. 



Specimen V (figures 19 to 22 and 45 to 48) 



As in the preceding, the entire endocranial cast of this speci- 

 men also is preserved. The maximum transverse diameter of 

 the cerebral portion of the cast is 4.7 cm. and its interpyriform 

 maximum is 4.6 cm. The maximum fronto-occipital diameter is 

 4.5 cm., while the greatest height of the cerebral portion is 3.3 

 cm. The maximum transverse diameter of the cerebellar por- 

 tion of the cast is 3.6 cm. and the maximum ponto-dorsal height 

 is 3.2 cm. The volume of the cerebral portion of the cast is 

 39 cc, while that of the cerebellum and brain stem combined is 

 15 cc. 



