THE BRAIN IN THE EDENTATA. 363 



of Stroud *, who has shown that it arises at an early period of development in Man and 

 the Cat. 



The lolms fiocculi consists of two morphologically distinct parts, which, adopting 

 Stroud's nomenclature, we may call the Jloccnlus and paraflocculus resj)ectively. Of 

 these the latter is very much Iragcr than the former, which it flattens against the 

 cerebellar peduncles and completely hides from view. The i^arajlocculus is a large 

 mass of an oval outline, which forms the greater part of the lateral pole of the cere- 

 bellum, being adapted to the lateral aspect of the colmnna cerehelU. It is 20 mm. 

 long and 16 mm. broad, and is placed obliquely, and more especially upon the caudal 

 aspect of the pole of the cerebellum. In a view of the cerebellum from above the 

 paraflocculus is visible as a crescentic area fringing the lateral and postero-lateral 

 margins of the organ. In a caudal view of the organ the paraflocculus is seen as an 

 obliquely-placed tapering mass extending from the lateral pole downward and mesially. 

 The paraflocculus is divided by an arcuate fissure into two parts, which we may d 

 tinguish as the paraflocculus ventralls and the pjara flocculus dorsalis. The former is 

 crescentic, and consists of eight simple folia, and behind these of a bimch of three folia 

 on one stalk. The. paraflocculus dorsalis con^iat^ of four branches of radiating fissures, 

 together forming an arc above the ventral part of the paraflocculus. The flocculus 

 consists of a broad flattened grouj) of folia which are hidden under the posterior j)art of 

 the ventral paraflocculus and adapted to tlie dorsal surface of the tuherculum acustlcum 

 later ale. 



After subtracting the two lohi flocculi, the rest of the cerebellum may be divided for 

 descriptive purposes into three azygos lobes, a cephalic, a caudal, and an intermediate or 

 central. 



The cephalic lobe, which we may call the lohus anticus, is separated from the rest of 

 the cerebellum by a fissure which we may distinguish as thefissurapritua. This is the 

 deepest fissure which crosses the mesial plane of the organ ; it is the most constant 

 fissure in the mammalian series, and is ever jJi'esent, separating the two simple folia 

 which form the greater part of the simple cerebellum of Notoryctes, and in addition it is 

 the first of the fissures wjiich cross the middle line to make its appearance in the course 

 of development, as Stroud and Kuithan have independently demonstrated. It is a 

 fissure of the greatest morphological importance, ranking in tliis res2)ect with the 

 fissura flocculi only. It corresponds to the " sulcus fur calls" of Stroud, the "sulcus 

 primarius cerehelU " of Kuithan. In human anatomy quite subsidiary importance is 

 attached to this fissure under the name '' flssura prceclivalis." 



In a mesial sagittal section this flssura prima may be seen cutting very deeply into the 

 organ from the dorsal surface, and extending almost to the recessus superior of the fourth 

 ventricle. In this plane it divides the organ into two approximately equal areas, the 

 anterior of which corresjjonds to the lohus aulieus. Regarding the dorsal surface of the 

 organ, this fissure may be seen to cross the middle line slightly in front of a point midway 

 between the cephalic and caudal limits of the organ. It extends transversely for about 



* Stroud, iijt. cit. p. 9-5. 



