250 MR. ST. GEORGE MIVART ON IN ORIS DIADEMA. [Mai*. 14, 



in I. laniger, the third cusp of the exteniiil cingulum being more 

 developed than in the first upper molar. 



The third upper molar is relatively smaller than in either of the 

 other genera of Indrisinee. It has indeed two anterior cusps, one 

 external, and the other internal ; but these are much smaller than 

 are the principal cusps of the more anterior molars. Behind these 

 the posterior part of the tooth has a slightly irregular surface and 

 margin, but is without any distinct cusps. 



The inferior incisors and canines are quite like those of /. lanir/er, 

 except that the inner surface of each canine has a wider groove than 

 even in /. brevicaudatus, owing to the greater development of the 

 lateral external prolongation of the basal cingulum. 



Inside of left half of mandible. Scale, nat. size. 



The anterior lower premolar is very much like that of /. laniger, 

 but is more vertically and less antero-posteriorly extended than even 

 in /. brevicaudatus. 



The posterior lower premolar is quite like that of /. laniyer, ex- 

 cept that the median longitudinal ridge does not extend upwards as 

 far as the external margin of the tooth does, though it does so rather 

 more than in the short-tailed form. 



The first lower molar is distinctly quinquecuspidate, the two pro- 

 cesses of the antero-external cusp of /. laniger being here distinct 

 cusps. In other respects it quite resembles its homologue in that spe- 

 cies. The same is the case, at least sometimes, in /. brevicaudatus. 

 This tooth has a great resemblance to the lower molars of many 

 insectivora, the three anterior cusps together forming a triangular 

 prism with one angle turned outwards ; while the postero-internal 

 angle of the prism is connected by a ridge with the molar's postero- 

 external cusp. 



The second molar resembles the first, except that there are but 

 four cusps (the most anterior of the three internal ones of the first 

 molar aborting), that the antero-internal cusp is more vertically ex- 

 tended, and the antero-external one less so, and finally that (as in 

 7. laniger) the anterior half of the tooth is not narrower transversely 

 than is its posterior half. 



The third and last lower molar is like that of I. brevicaudatus, 

 and has its supplemental fifth (posterior) cusp rather more developed 

 than it is in I. laniger. 



