'>>>. PHYSIOLOGICAL SERIES. 



oblique pseudosylvian sulcus, like that of the Bears, with 

 an extensive suprasylvian arc presenting such an acute 

 flexure as is seen only in the Arctoid Carnivores (of existing 

 mammals). To complete the resemblance, the area between 

 these two sulci is depressed, as it sometimes is in the Bears, 

 and always in the Seals. There was an orbital sulcus and a 

 lateral sulcus of the typical Carnivore pattern. In front of 

 the latter there was a great transverse sulcus, like tho 

 crucial sulcus ; this may, however, be the coronal sulcus. 

 Gervais, Nouv. Arch. Mus., t. v. 1869, p. 39. 



D. 280. A cast of the cranial cavity of a Pampean Ground-Sloth 

 (Grypotherium listai). 



" Compared with the brains of Mylodon and Scelido- 

 tJierium, . . . that of Grypotherium is observed to be more 

 elongated, with less divergent and prominent olfactory 

 [bulbs] , less constricted cerebral hemispheres, and a larger 

 cerebellum. In the form and proportions of its cerebellum, 

 it similarly differs from Megatherium. The cerebral hemi- 

 spheres of the existing Choloepus didactylus and Bradypus 

 tndactylus are more tapering forward, and their cerebellum 

 is relatively smaller than in Grypotherium?' (Smith Wood- 

 ward, Proc. Zool. Soc. 1900, p. 69.) 



The cast shows only in a very vague manner the arrange- 

 ment of pre- and suprasylvian sulci, resembling those of 

 Choloepus. This specimen is, moreover, interesting as 

 an illustration of the caution needed in drawing infereix -e- 

 from the general shape of a cranial cast ; for if the olfac- 

 tory bulbs were broken, as so commonly happens, and the 

 sulci a little more blurred, one might easily mistake thi< 

 for the cast of some Dugong-like Sirenian. 



Family MYRMECOPHAGID^S. 



D. 281. Tho brain of a Great Anteater ( Myrmecophaga jubatd). 

 The right cerebral hemisphere has been separated from ihe 

 rest of the brain. [This drawing of the riyht hemisphere 

 has been reversed.] 



The elongated form of the cerebral hemispheres presents 

 a marked contrast to that of the Sloths. The olfactory 

 bulbs are very large. 



