THE BRAIN IN THE EDENTATA. 369 



alike. Kuitliaii has unhesitatingly called the analogous part of tlie Sheep's hraiu by 

 the name ^' fijramid^'' although its disposition agrees exactly with the corresj)onding 

 part in Orycteroptis. In the meantime I shall use the term pyramid witli the 

 reservation that the validity of its homology with the similarly-named part of the 

 cerebellum in Man remains to be joroved. This point can be satisfactorily settled 

 only by embryological investigation, and neither Kuithan nor Stroud has attempted 

 to solve the problem. 



After we have learned how closely the cut surface of the cerebellum which is exposed 

 in a mesial sagittal section in Ori/cteropus agrees with the arrangement in the brain of 

 Man and the Sheep, it is not surprising to find the closest agreement between Orycteropiis 

 and Myrmecopliucja in this respect. So exact is this resemblance that fig. 29 would 

 need only very slight modification to represent a section from the Great Ant-eater. 

 But the agreement is not confined to the mesial section. For in the behaviour of the 

 lateral extensions of the parts we again find a close resemblance between the two organs. 

 In Myrmecophaga the lateral parts are not so full and rounded as they are in Orycte- 

 ropns, and hence the organ approaches nearer to a lozenge-shape. The descriptions we 

 have given of the Jissiira prima and the lobiis loilicits in Orycteropiis apply equally well 

 to Myrmecophacja. The lohus flocculi is relatively smaller in the Ant-eater, and does 

 not rise nearly so high as it does in the Aard-vark. Both the dorsal and ventral parts of 

 the j^araflocculus are horizontal worm-like l)ands, and the dorsal part especially is much 

 narrower than it is in the Aard-vark. In addition it is much simpler (fig. 7). The 

 fiocculus is more exposed than it is in the Aard-vark. 



The area A of the lohus centralis is moreover somewhat simpler than it is in 

 Orycteropiis. As a result of the smaller size of the lobus flocculi, the area B overlaj)s 

 it to a greater extent than is the case in the Aard-vark. The area C closely resembles 

 the corresponding region in our type, but the mesial region with which it is connected 

 is submerged. 



The lateral extensions of the pyramid have more obvious bands than is the case in 

 Orycteropus, and thus they appear to form the lowermost folia of the area C. 



T'he cerebellum of Tamandiia is smaller and simjiler, and jn'esents several slight 

 differences to mar tlie otherwise close resemblance to the organ in the Great Ant-eater. 

 The main features of the anterior lobe are imchanged, but its structure is simplified by a 

 reduction in the number and complexity of the folia. 



The general features of the lobus flocculi resemble those of Myrmecophaga, but the 

 band connecting the posterior extremity of the dorsal part of the paraflocculus to the 

 pyramid now appears to be quite aborted. In a superficial view the folia of the posterior 

 extremity of the paraflocculus appear to be in series with the folia of the area C of the 

 lobus centralis. The posterior extremity of the ventral parafloccukis is peculiarly 

 modified to form a projecting tuft of about six folia on a common stalk. This is lodged 

 in a special cavity of the periotic bone, and in the loose nomenclature in common use 

 would be called simply " flocculus." 



The area A of the central lobe is a single folium which is cut up by a few shallow 

 sulci, not visible on the surface. The area B is a simplified copy of the corresponding 



