78 THE DESEADO FORMATION OF PATAGONIA 



orous Oligocene oreodont, Eucrotaphiis, an animal of 

 approximately the same size, this brain is half again as 

 large in every way. A second striking feature is the short 

 compact character of the brain, the forebrain extending 

 only a short distance in front of the exit of the optic nerves, 

 and extending backward so as to cover most all of the cere- 

 bellum. Thirdly, the cerebral surface is considerably con- 

 voluted, comparable to the convolution of a pig's brain. 

 These features would indicate a specialization of the nerv- 

 ous system, approximating that of the skeleton, and 

 would indicate that this group had advanced in intelli- 

 gence and activity beyond the grade of nervous develop- 

 ment which is apparent in the contemporaries of the 

 Ty pother ia. 



The relatively small olfactory lobes arc entirely beneath 

 the frontal lobes and are seen only on the side view, but 

 as there is a large hippocampal lobe behind them, it would 

 only seem proper to attribute to these animals a well- 

 developed sense of smell. The frontal lobes are unexpect- 

 edly large, and are not clearly bounded off from the parietal 

 lobes. The occipital lobes are also well developed and make 

 a large portion of the backward extension of the cerebrum. 

 The large size of this area, together with the fact that the 

 optic nerves are large, indicates a good visual development. 

 The temporal lobes are also large and extend well down on 

 either side. And, finally, below all the others, come the 

 swollen hippocampal lobes which complete this large cere- 

 brum. 



The cerebellum is small having neither considerable 

 width or height, and being overlapped by the cerebrum. 

 The optic nerves are represented by large projections leav- 

 ing the twixt-brain well forward under the forebrain. 

 The medulla is not clearly marked except to show that it, 

 too, was of fair size. 



Just behind the hippocampal lobes, and connecting with 

 the cerebellum appear two striking projections. These 



