NERVOUS SYSTEM. VERTEBRATA. 203 



corresponds to the coronary, and the posterior to the lateral 

 sulcus of other Orders. The adjacent ends of both sulci 

 are bifid. 



There are a number of other sulci on the cranial surface 

 of the hemispheres, but they are so unstable that they 

 differ considerably on the two hemispheres of the brain 

 and to a much greater extent in different brains. 



It is the sulci (or rather the absence of sulci) on the 

 mesial surface of the Rodent's brain by which the aberrant 

 character of this Order is indicated. The rhinal fissure 

 extends high up on the mesial surface (of the Capybara' s 

 brain) parallel to the hippocampal fissure. The most 

 striking fact, however, is the insignificant representative of 

 the calcarine sulcus. There is only a small sulcus behind 

 the splenium of the corpus callosum in the situation where 

 we should expect the deep long calcarine sulcus. In most 

 Rodents even this is missing, and in this brain the features 

 of this small furrow are such as to render its homology 

 somewhat questionable. But even granting that this 

 sulcus in the Capybara is the true calcarine, its insig- 

 ficance is very peculiar when we recall that in all other 

 Eutherian Orders as well as in the Metatheria the deep, 

 long calcarine sulcus is the most constant and best defined 

 of all the sulci of the neopallium. 



In the Capybara again, as in all Rodents, there is no 

 intercalary sulcus, if we except the insignificant furrow 

 near the upper surface of the splenium. 



There is, however, a well-defined genual and also a 

 large rostral sulcus. 



The cerebellum is remarkable for its small size and 

 compactness (fig. 71). Its folia are arranged in a 

 simple transverse pattern, and as a result there is a close 

 resemblance to the type prevalent in the Ungulata. 

 There is a large floccular lobe. 0. C. 1323 G d. 



Beddard, Proc. Zool. Soc. 1899, p. 798. v 



Holl, Arch. f. Anat. und Phys. (Anat. Abth.) 1900, p. 295. 



D. 255. The brain of a Capybara (Hydroclicerus capybara) ( $ ) , 

 in which the left hemisphere has been dissected to show 

 the corpus callosum, 



