160 FIELD MUSEUM or NATURAL HISTORY ZOOLOGY, VOL. XIV. 



Perameles, though the elephant-shrew, Macroscelides, has a cerebellum 

 but little more complex than that of Perameles (Elliot Smith, 'oab). 



The cerebellum is composed of a simply organized transverse body 

 and the two lateral floccular lobes. (In the preparation of the brain the 

 left flocculus was destroyed. In the figures it has been restored after the 

 one on the opposite side.) Each flocculus is mushroom-shaped with a 

 slender pedicle and a widely expanded cap or pileus, whose surface is 

 somewhat lacerated but apparently was smooth or nearly so. 



The body of the cerebellum, so far as it is visible from the surface, is 

 a transverse bar with two shorter convolutions under its posterior border. 

 The main bar consists of a plump median lobe and two lateral lobes, 

 each of which is somewhat less than half the length in th transverse 

 plane of the medial lobe. The median lobe and the two smaller posterior 

 convolutions apparently correspond with the vermicular portion of 

 higher cerebella and the lateral lobes with the hemispheres. 



Since only a part of the cerebellum is visible in the undissected 

 specimen, it is impossible to determine with certainty the homologies 

 of the exposed structures. But comparison with the very similar 

 cerebella of Notoryctes and Perameles as described and figured by Elliot 

 Smith ('osa and 'o3b) suggests that in Ccenolestes the lobus anterior and 

 fissura prima are entirely concealed in the transverse fissure between 

 the cerebellum and the cerebral hemispheres, the transverse bar is the 

 lobus medius, the fissure limiting it posteriorly is the fissura secunda, the 

 first of the two shorter convolutions is the uvula, the fissure behind the 

 latter is the fissure postnodularis, and the posterior one of the shorter 

 convolutions is the nodulus, these names being used as defined by 

 Elliot Smith ('oaa). 



The brain stem. On the ventral surface (PI. XXII) the optic nerves 

 are seen to be very slender. Behind the optic chiasma is a rather wide 

 tuber cinereum whose surface is somewhat obscured by meninges which 

 in view of the poor state of preservation of the specimen it seemed 

 inexpedient to attempt to remove. The pituitary body is mushroom- 

 shaped and elevated on a very short infundibular stalk. On account 

 of the flexure of the brain in the isthmus region the cerebral peduncles 

 are entirely concealed. Stumps of the third and fourth cranial nerves 

 are seen in the usual relations. 



The medulla oblongata under the cerebellum is very wide. The 

 sculpturing^ of the ventral surface is obscured by pressure against the 

 floor of the cranial cavity and posteriorly by a blood clot in the meninges. 

 Nevertheless the roots of all of the cranial nerves were identified. The 

 trigeminus is large, arising from the posterior border of the pons, which is 

 very slender. The abducens is very minute and is recognized (with 



