216 PHYSIOLOGICAL SERIES. 



parallel to the posterior two-thirds of the interlicmi- 

 spheral cleft. It also crosses on to the caudal surface of 

 the hemisphere and approaches, though it usually doe- n<.i 

 join, the upper extremity of the vertical calcarine This 

 arrangement, which does not occur in the Garni vora, is of 

 considerable interest in view of the relationship which e.\i-t> 

 between the calcarine and intraparietal (the probable 

 representative of the lateral) sulcus and the newer inter- 

 calated parieto-occipital sulcus in certain of the Primates 

 (vide infra). 



The anterior extremity of the lateral sulcus (fig. 88, 7) is 

 overlapped on its lateral aspect by a short sagittal sulcus 

 (/), which may possibly represent the coronal sulcus of 

 the Cat's brain (vide infra) . 



There is no crucial sulcus. 



The mesial surface (compare figs. 89 and 90) [which i- 

 not exposed in this specimen] resembles that of the Two- 

 toed Sloth in all its essential features (vide specimen D. 27;")). 



The cerebellum appears to be relatively very small. The 

 floccular lobes are large cake-like masses flattened against 

 the lateral aspect of the organ. Each of these lobes is com- 

 posed of the usual three parts, flocculus and dorsal and 

 ventral paraflocculi. In marked contrast to the condition 

 found in the Armadillos [vide Cabassous, fig. 83], the dorsal 

 paraflocculus is much the largest part of the floccular loin- 

 in the Sloth. The rest of the cerebellum is small, narrow 

 and simple. Its lateral parts are not expanded to the s;un< 

 extent as the corresponding parts in the Carnivores, tin- 

 Anteaters, or even the Armadillos. In this respect the cere- 

 bellum much more closely resembles that of such form- a- 

 Uorcatlierium (Ungulata) and Ilydrochcerus (Rodentia). 



0. c. i:$23 H b. 

 Elliot Smith, Trans. Linn. Soc. vol. vii. 1899, p. 2%. 



D. 274. The brain of a Three-toed Sloth (Bradypus tridactylo*} 



( ( ), enclosed in the vascular pia and arachnoid membrane.-. 



In this specimen the independent intercalary sulcus can 



be seen on the mesial surface. The coronal and lateral 



sulci seem to be fused. 0. C. 1323 11 a. 



