296 DAVIDSON BLACK 



maximum front o-oecipital diameter, 4.5 cm.; maximum cerebral 

 height, 3.2 cm.; vokuiie of cerebrum, 36 cc; volume of cerebellum 

 and brain stem, 14 cc. 



The figures given by Flatau and Jacobsohn (15) for Sus scrofa 

 domesticus, so far as they can be used for comparison, are as 

 follows: Maxim vmi transverse cerebral diameter, circa 4.5 cm.; 

 maximum fronto-occipital diameter, 7.3 cm. ; maximum cerebral 

 height, 4.0 cm.; maximum transverse cerebellar diameter, 4.2 

 cm. Sus is made use of in this connection since its size approxi- 

 mates that of Oreodon. 



A comparison of the figures shows the larger size of the adult 

 pig brain especially evident in the fronto-occipital diameter, 

 while in maximum transverse cerebral diameter Sus and Oreodon 

 (respectively 4.5 cm.; 4.6 cm.) are practically the same, when it 

 is recalled that the measurement in Oreodon is from the endo- 

 cranial cast. 



My own series of formalin hardened pig brains are all from 

 young animals so that linear comparisons with Oreodon are not 

 practical. It is of interest to note, however, that the volume 

 of the cerebrum in my specimens ranges from 55 cc. to 60 cc. 

 and this, though it must fall considerably below the volume of 

 the adult cerebrum, is yet far above the average volume of the 

 cerebrum in the Oreodon specimens. 



Such disparity is not so obvious on comparing the cerebellar- 

 brain stem volumes of Oreodon and immature Sus, since in the 

 latter the average was but slightly above 14 cc. The difference, 

 however, is somewhat greater than would at first sight appear 

 since among other things the average volume of this region as 

 determined for Oreodon is that of the endocranial cavity while 

 in the Sus specimens measured it corresponds to brain parts only. 



The above comparisons, though admittedly only approximate, 

 are not lacking in significance since they serve to show, 1) that 

 in Oreodon the cerebrum had attained a transverse diameter 

 approximately equal to that obtaining in adult modern Sus; 2) 

 that a great discrepancy is evident in the fronto-occipital growth 

 of the brain of Oreodon as compared with Sus; 3) that the volume 



