300 PHYSIOLOGICAL SERIES. 



The suprasylvian sulcus is here bent at right angles ami 

 opens into the anterior rhinal fissure. There can be no 

 doubt concerning the small postsylvian sulcus in this brain. 

 The orbital sulcus appears to be missing. The coronal 

 sulcus is prolonged in a peculiar manner. 



A comparison of this specimen with the preceding at once 

 explains the apparent discrepancy between the accounts of 

 Turner (op. cit.) and Krueg (op. cit.) respectively. 



D. 389. A cast of the cranial cavity of a Hyrax (Procavia capensis) . 

 [In duplicate.] 



The olfactory bulbs project well in front of the hemi- 

 spheres. In addition to the constant sulci, there is a well- 

 developed vertical postsylvian and also a faint indication of 

 an orbital sulcus. 



Extinct Suborder AMBLYOPODA. 



D. 390. A cast of the cranial cavity of Dinoceras mirabile. 



This cast proves conclusively that the brain of this 

 Eocene mammal, which nearly equalled the Elephant in 

 size, was proportionately smaller than that in any other 

 known mammal, recent or fossil, and even less than in 

 some reptiles. 



Its general appearance is not unlike that of many reptiles, 

 and the colossal size of the olfactory bulbs leads us to infer 

 that the diminutive cerebral hemispheres must have been 

 almost wholly composed of pyriform lobe, tuberculurn 

 olfactorium, and hippocampus (together with the corpus 

 striatum). 



The neopallium could not have been much greater than 

 it is in Reptile-, in which it is so insignificant that it lias 

 hitherto never been definitely described as such. It i.- 

 unlikely that any rhinal fissure had yet developed, and 

 probably the hippocampus constituted the whole of the 

 me>i:il surface of the hemisphere, as it does in Reptiles. 



The >imple leaf-like cerebellum must have closely re- 

 sembled that of the Marsupial Mole (NotoryHes). 



Marsh. American .lourn. of >Sci. and Art. \ol. \i. |.s?il. 

 p. 165. 



