377 



appendage is the lobus flocculi: a shallow groove on its surface in- 

 dicates the separation into a smaller ventral part or flocculus (which 

 is continuous mesially with the ala noduli) and a dorsal part or para- 

 flocculus (which is in free continuity with the lobus medius by means 

 of the copula pyramidis). It is further to be noted that whereas the 

 stratum granulosum of the flocculus and paraflocculus is freely con- 

 tinuous, it is not joined to that of the rest of the cerebellum (except 

 by means of the mesial prolongations of the copula pyramidis and 

 ala noduli). 



Another feature which must be emphasised is that the fissurae 

 parafloccularis, secunda and postnodularis are each independent of any 

 other furrows and the one of the other. 



In the particular adult cerebellum of Notoryctes which I hap- 

 pened to select for the purpose of making this series of sections there 

 were no other fissures in the organ except those already enumerated 

 i. e. the fissurae prima, secunda, postnodularis and parafloccularis. 

 In two other specimens, however, I found a fissura suprapyramidalis ; 

 whereas in my type - specimen this furrow was indicated only by a 

 notch in the stratum granulosum (Fig. 5 x), which did not involve the 

 stratum moleculare or the surface of the organ. In one specimen this 

 suprapyramidal fissure was widely extended on both sides (Fig. 13), 

 probably representing a confluence with two laterally placed parapyra- 

 midal fissures. 



In two specimens a pair of postlunate fissures was present on 

 the anterior surface (Fig. 12) and in one specimen there was a small 

 laterally-placed fissure on each side of the posterior aspect (Fig. 4 y) 

 possibly representing the earliest phase of the fissura postpteroidea. 

 The identity of this fissure is, however, by no means certain. 



The cerebellum in Perameles is considerably larger than it is 

 in Notoryctes and is slightly more complex. Thus the anterior 

 lobe, instead of being simple and smooth, is subdivided by two deep, 

 and often also by two or three shallow, furrows (op. cit. infra, 8, 

 p. 427): the suprapyramidal fissure (which is more constant than in 

 Notoryctes, but may sometimes be absent) becomes confluent with 

 the parafloccular fissures so that the copula pyramidis is visible on 

 the surface. Independent parapyramidal fissures are constantly pre- 

 sent and occasionally a fissure analogous to that labelled y (Fig. 13) 

 in Notoryctes. Occasionally a small laterally placed fissure makes 

 its appearance on the anterior surface just above the fissura post- 

 lunata and raises the question (which is at present insoluble) as to 

 the identity of the fissura postpteroidea. The paraflocculus is sepa- 



