280 DAVIDSON BLACK 



In the iiiidclorsal line the elevation corresponding to the supe- 

 rior sagittal sinus is prominent. This ridge increases in size 

 from before backward and is lost in the tentorial groove on the 

 right side. There is, however, an indication of a small channel 

 draining to the left on this specimen (v. fig. 3). 



(Left, figs. 1 and 27.) The conditions on the left side of this 

 specimen closely approximate those on the right except for the 

 juncture of the suprasylvian and corono-ansate sulci as already 

 noted. 



On both sides of this specimen the gyri surrounding the rostral 

 extremity of the coronal sulcus are very prominent. Between 

 these two prominent bosses a well marked quadrangular depressed 

 area occurs on the dorsorostral surface of the cast. The most 

 prominent gyri on the cerebral surface other than the coronal 

 bosses are those on each side of the cast which lie between the 

 suprasylvian and the caudal halves of the lateral sulci. 



Specimen II (figs. 5 to 10 and 31 to 36). 



In the preparation of this specimen, throughout its whole 

 dorsal endocranial surface the fossilized skull bones showed a 

 strong tendency to adhere to the softer underlying natural cast. 

 For this reason a record was kept of the course of the cerebral 

 fissures, etc., during the progress of enucleation of the cast while 

 in the cerebellar portion it was found more practical to clean the 

 endocranial surface of the skull fragments and make a plaster 

 cast of the reassembled parts. 



The greatest transverse diameter of the cerebral portion of the 

 natural cast is 4.5 cm. while the maximum interpyriform diam- 

 eter is 4.5 cm. The maximum fronto-occipital diameter of the 

 cerebrum is 4.4 cm. and its maximum height is 3.3 cm. The 

 maximum transverse diameter of the cerebellar portion of the 

 cast is 3.3 cm, and the maximum height from the basi-occipital 

 or pontine surface to the dorsum of the cerebellum is also 3.3 

 cm. The volume of the cerebral portion of the cast is 33 cc, 

 that of the cerebellum and brain stem being 13 cc. 



Brain stem and basis cerebri. (Fig. 8.) The general plan of 

 the structures in relation to the basis cerebri in this specimen is 



