1882.] oGo [Cope. 



than long, but they probably pass gradually into the mesencephalon be- 

 hind them. These bodies remind one of the corpora olivaeformia, and 

 may represent the superior or median frontal convolutions. They are 

 probably, however, not to be homologized with any convolutions, repre- 

 senting rather the cerebral vault of the lateral ventricle. Posterior to 

 them the flat surface descends gently without indication of copora quadri- 

 gemina or other irregularity, and at a distance about equal to the length 

 of the oval bodies, it begins to rise gently. The cranium is broken here, 

 and no cast of the cerebellum was obtained. 



I may remark that the cranium from which this cast is taken is not 

 crushed, and that it consists of pa"rts of the parietal and squamosal bones 

 only. The latter remain as far as the incurvature to the pterygoid pro- 

 cesses in front of the glenoid cavity. 



Measurements of hrain. M, 



Length from posterior rise to base of olfactory lobes 037 



Length of oval bodies of hemispheres 018 



Width of proximal part of olfactory lobes 027 



Width of olfactory peduncles 021 



Length from olfactory lobes to oval bodies of hemis- 

 pheres 005 



Diameter of hemispheres at posterior part of oval bodies. .038 

 Depth from sagittal crest to olfactory lobes 024 



EXPLANATION OF PLATES. 



Plate I. 



Casts of the brain case of Phenacodus jirimcevus Cope, natural size. 



Fig. 1. Lateral view. 



Fig. 2. Superior view. 



Fig . 3. Anterior view. 



Fig. 4. Posterior view. 



Plate II. 



Fig. 1. Brain of Phenacodus primcems, inferior view. 



Fig. 2. Cast of brain case of PeriptycMs rhabdodon, superior view. 



Fig. 8. Cast of brain case of PeriptycJius rliahdodon, lateral view. 



