THE BEAIN IN THE EDENTATA. 381 



factor must be mucli greater than it is in any Armadillo or Rodent, we still find the 

 anterior lobe covered by the hood-like central lobe. In view of these facts and the 

 marked contrast between the cerebellum in Chlamydopliorus and. Notori/ctes, we are 

 justified in attaching some importance to the degree of development of the cerebellum as 

 an index of the status of its possessor. 



The enormous growth of the " area crescens " of the central lobe in the Primates, 

 and the very different configuration and size of the corresponding part of the cerebellum 

 in the Monotremata, show us that there is some other very definite factor besides 

 bodily dimensions which determines the size of the cerebellum. The quantity and 

 quality of the jiallium undoubtedly have a marked effect upon the proportions of the 

 cerebellum. 



If we regard the evidence of the cerebellum as having a definitive taxonomic value— 

 and in view of the configuration of this organ in Monotremata and Primates, in comparison 

 with the large group of other mammals, it is difficult to do otherwise — then we must 

 attach some importance to the extremely close resemblance in configuration and pro- 

 portions which exists between the cerebellum of the Ant-eaters and Aard-vark and of 

 the Carnivora and Ungulata. The fact that such a highly specialized organ as the 

 cerebellum should develop along such exactly analogous lines and attain such similar 

 proportions in these different groups of animals most conclusively shows, when we 

 remember how wide a scope for variation there is, that here we have an instance either 

 of a most remarkable case of convergence or parallelism (which is exceedingly improb- 

 able), or an imassailable indication of the close genetic relationship which exists between 

 the Edentates and the commoner quadrupedal mammals. 



The idea of separating the Edentata from such other mammals as the Hodentia, 

 Ungulata, and Carnivora, implied in the introduction of the term " Faratheria," or the 

 belief that " they suddenly shot up from the Prototheria " *, is entirely shattered by the 

 evidence of the cerebellum, even if we had not the testimony of the other anatomical 

 systems to the same jDui-pose. 



Am.ong the extinct Armadillos we find in Eutatus a cerebellum of the simpler 

 Armadillo-type, while in Glyptodon we find an enormous cerebellum which probablv 

 resembled that of Dasyims. 



It is an interesting problem to determine what may have been the reason for a 

 cerebellum of such huge dimensions in Glyptodou, for the organ is as large as a cerebral 

 hemisphere. While the pallial factor must have been ver}^ slight, it may be that the 

 somatic factor explakis the large dimensions of the organ. For it is conceivable that an 

 animal of such large proportions would need a large organ to co-ordinate its great 

 muscular system, even though the commanding pallium, which renders such a co- 

 ordinating mechanism necessary, should be so diminutive. 



In describing the brain of 3Ii/rmecophu(ja I had occasion to call attention to the 

 undoubted fact of its being fashioned in the likeness of the Carrdvorous type. At the 

 same time it was shown from Max Weber's statistics that Carnivores of similar body- 



* \V. K. Parker, ' Mammalian Descent.' 

 SECOND SERIES. — ZOOLOGY, VOL. VII. 52 



