THE UIIATN OF THE LEMUKS. 



85 



an examination of the mesial aspect of the hemisphere (fig. C). 

 In this specimen 12 mm. out of a total length of 31 mm. lie on 

 the caudal aide of the splenium of the corpus callosum ; whereas 

 in an adult Lemur fulvus only 11 ram. out of a total length of 

 41 mm. lie behind the splenium. 



There is a typical coronal sulcus (s.co.) with a bifid posterior 

 extremity such as commonly occurs in the genus Lemur (Mem. 

 fig. 1), Glohilemur (Mem. tigs. 39 & 40), and, perhaps, in 

 Indris (Mem. fig. 30). This exact form of coronal sulcus was 

 present in only one (Mem. fig. 29) of the crania of Propithecus 

 examined. 



Both the orbital and diagonal sulci present a simple linear 

 form, and occupy that peculiar position entirely within the 



SJTC, 



orbital area which seems to be so characteristic of the Indriainse 

 (Mem. fig. 28). Tiie orbital sulcus is placed Tery close to and 

 parallel with the olfactory bulb, whereas the diagonal sulcus is 

 parallel to and entirely below the orbital margin. 



As we have already noticed in some of the casts oi Frojyitliecus 

 (Mem. fig. 22), the sulcus /' {i. e. the supposed dorsal element 

 of the central sulcus) is distinctly transverse, and not oblique as 

 in Lemur and Nycticehus. 



This specimen resembles Indris and differs from all my speci- 

 mens of Propithecus (with the possible exception of that repre- 

 sented in Mem. fig. 29) in regard to the form of the Sylvian fissure 

 and the lateral sulcus. The latter (fig. B, si.) is exceedingly 



