18G6\] MR. ST. GEORGE MIVART ON MICRORHYNCHUS. 165 



proportion of the same bone to the radius is only 142 to 100, while 

 in Indris it is 18 3. 



The femur is wanting in the specimen described ; but De Blainville 

 says* it about equals the length of the tibia, which last is, as com- 

 pared to the radius, as 149" 1 to 100, and is very much compressed 

 laterally, and strongly concave on its peroneal side. 



The fibula is relatively, as well as absolutely, rather more slender 

 than in Indris, and still more so than in Lemur. 



The tarsus differs from that of the last-named genus in its rather 

 longer astragalus, in its relatively shorter cuboid, which, compared 

 to the os calcis, is only 37'6 to 100, instead of 460 as in Lemur. 

 Indris closely resembles Microrhynchus in this respect, as its cuboid 

 is to its calcaneum as 38'6 to 100. 



The cuboid of M. laniger is also less deeply grooved for the tendon 

 of the peronaeus longus than is that of Lemur. 



The metatarsals are absolutely and relatively longer than in that 

 genus, that of the hallux greatly exceeding the os calcis in length, 

 while in Lemur it does so very slightly. 



When, in the autumn of 1864 -f, 1 endeavoured to clear up some 

 of the confusion existing with regard to certain kinds of Lemuridce, 

 I regretted being able to say so little regarding the Indrisinre, no 

 extracted skull of either Propithecus or Microrhynchus then existing 

 in this country. 



From a consideration of the figures extant of the cranium of the 

 last-named genus I ventured on a decided opinion that those had 

 rightly decided who associated it with Indris, and that it could by 

 no means be separated from that form and approximated to Galayo. 



The examination of the specimen now described fully confirms this 

 view ; indeed so numerous and striking are the points of resemblance 

 between it and Indris that it is a matter of some difficulty to find 

 distinctive characters sufficient to justify even their generic separation. 



Unfortunately I have had no opportunity of examining any ex- 

 tracted cranium of Propithecus ; but I strongly suspect that when 

 obtained it will be found closely to resemble the two other genera of 

 Indrisince, as the dentition, as far as can be seen in the mounted 

 specimens in the British Museum, so closely agrees with that of 

 Indris. That subfamily may, I think, be characterized as follows : — 



Indrisince. 



Characters*.— I. *=?. C. £j. P.M. *-=?§. M. |^=30. 



Ears short ; muzzle long, moderate or short ; hind legs much 

 longer than the fore limbs ; index very short, much shorter than 



* Loc. cit. 



t See Notes on the Crania and Dentition of the Lemuridce, P. Z. S. 1864, p. 61 1. 



f The cranial, most of the dental, and some other characters are, of course, 

 drawn from Indris and Microrhynchus only, and may have to be curtailed or 

 modified when the structure of Propithecus is better known. 



§ The immature condition of the teeth of Propithecus represented in M. de 

 Blainville's plate led me, in 1864, to the conclusion that there are, as stated, two 

 premolars and three molars on each side of each jaw. (See P. Z. S. 1864, p. 634.) 



