NERVOUS SYSTEM. VERTEBRATA. 187 



hemispheres and the projecting olfactory bulbs, as in the 

 Kangaroos. The cerebral sulci are very deep farrows, 

 conforming to the same pattern as in the brain (D. 222). 

 Gervais, Nouv. Archiv. Mus., t. v. 1869, p. 235. 



D. 224. The brain of a Wombat (Pliascolomys ursinus), dissected 

 to expose the dorsal or hippocampal commissure from 

 above. 



This dissection was made by the late Sir Richard (then 

 Professor) Owen to demonstrate that the dorsal commissure 

 of the Marsupial is derived from the fornix, i. e. that it is a 

 hippocampal commissure or psalterium (Phil. Trans. 1837, 

 p. 90; also Todd's Cyclopaedia, vol. iii. p. 294, fig. 117 ; also 

 'Anatomy of Vertebrates/ vol. iii.). 



The greater part of the cerebral hemispheres has been 

 removed so as to expose the upper surface of the dorsal 

 commissure, which may be seen passing into the fimbria 

 upon each side. 



On the right side the fascia dentata may be seen lying 

 upon the fimbria and extending obliquely across the upper 

 surface of the dorsal commissures so as to reach the mesial 

 surface of the hemisphere in front of the commissure. 



The corpora striata have been exposed in the lateral 

 ventricles. 



Part of the cerebellum has been removed so as to open 

 up the fourth ventricle. 0. C. 1323 A o. 



Family PHALANGERID^E. 



D. 225. The brain of a Brown Phalanger ( Triclwsurus fuliginosus) . 



In general appearance this brain is not unlike that of 

 the Rat-Kangaroos. It exhibits a shallow depression in 

 the situation where the characteristic paramedian sulcus 

 occurs in the smaller Macropodidse. Traces of a prorean 

 sulcus and that called " suprasylvian " in the Kangaroo are 

 present. 



Although the neopallium is much larger than that of 

 many of the smaller Polyprotodont Marsupials which 

 possess a well-defined orbital sulcus, the latter feature is 

 not clearly defined. 0. C. 1323 A m. 



Ziehen, Jena. Denkschr., Bd. vi. 1897, p. 84. 



