84 ALLEN'S NATURALIST'S LIBRARY. 



In the skull, the muzzle is longer than the longitudinal 

 diameter of its orbit in the series of larger species (Section A) ; 

 in the smaller species (Section B) the muzzle is shorter. 



Their dentition presents several important characters. The 

 series of upper molars and pre-molars form almost a straight 

 line, both sides being almost parallel, or only slightly convergent 

 towards the front. In the upper jaw the incisors are wanting ; 

 the canines are very large and grooved internally, and have a 

 posterior heel. There is no gap between them and the anterior 

 pre-molar, which last is vertically taller than the rest, and has one 

 cusp to the outside, whereas the median and posterior have an 

 inner cusp as well. The anterior and median molars have the 

 inner hind cusp rudimentary, but the cingulum rises into a 

 minute cusp, both at the fore and hind edge ; the posterior 

 molar is three-cusped. The whole of the cheek-teeth gradually 

 broaden and decrease in vertical height from before backward 

 as far as the median molar. In the lower jaw the anterior pre- 

 molars are large, canine-like, and decumbent, and have a strong 

 process on their anterior margin (resembling that in the corre- 

 sponding tooth in Indris) ; the median and posterior pre-molars 

 have one external cusp, and the latter tooth one interior cusp 

 in addition. The anterior and median molars have a rudi- 

 mentary fifth cusp, which is large in the posterior molar. 



The pre-maxillse are very much reduced, so that the teeth 

 they usually carry are generally wanting. The bony palate is 

 short, its hind margin extending back only to the middle of the 

 median molar ; its anterior foramina are small ; and it differs 

 from that of Microcebus and Chirogale in having its posterior per- 

 forations small. The angle of the lower jaw is produced down- 

 wards and backwards. The mastoid portion of the ear-capsules 

 (periotic bones) as well as the squamosal are markedly en- 



