186G.] MR. ST. GTCORGE MIVART ON MICRORHYNCHUS. lftl 



maxillary suture being almost on a line with the posterior margin of 

 the nasals, instead of considerably below it, as in a specimen of the 

 genus Indris in the British Museum*. Microrhynchus, however, 

 agrees with that genus in having no large malar foramen, as also in 

 having the lachrymal foramen rather nearer the margin of the orbit 

 than in the Lemuridaz, though it still opens upon the cheek. The 

 suture between the maxilla and the prsemaxilla is so far obliterated 

 in the specimen described that it is impossible to determine whether 

 the latter sends up a small process to join the nasal as it certainly 

 does in Indris; sometimes, though, judging from De BlainvihVs 

 figure, it does not quite reach the nasal. 



The floor of the orbit is very large, with many perforations, and 

 is placed so low down as to be but little above the alveolar margin of 

 the upper jaw. The malar is very wide, and its lower part is irre- 

 gular, forming a vertically ridged and grooved surface for the attach- 

 ment of the masseter, which surface is bounded above by an antero- 

 posteriorly directed ridge. The malar also developes, from its poste- 

 rior border, an obtuse processf (which projects backwards over, but 

 some distance above, the anterior extremity of the zygomatic process 

 of the squamosal), and extends back to very near the anterior margin 

 of the glenoid surface. 



The masseteric space, on the malar, is larger and more ridged than 

 in any other Lemnroid. In Indris the same thing exists, but in a 

 less degree, and the surface is more posteriorly situated. A similar 

 wide masseteric space is also present in the larger Galagos ; but it is 

 not ridged, and it approaches close to the upper alveolar margin ; 

 whereas in M. laniger it is kept at a distance from that margin by 

 the wide maxillary floor of the orbit, a structure which causes the 

 basis cranii of tfiis Lemuroid to differ strikingly in aspect from that 

 of any other member of the suborder. 



The glenoid surface for the lower jaw is strongly concave from 

 within outwards and faintly convex from behind forwards" at its an- 

 terior part, the outer end of this convexity forming a slight process, 

 which depends from the lower border of "the zygoma at a point just 

 in front of, and without, the spot which receives the condyle of the 

 mandible. This process is similarly developed in Indris; but I have 

 not seen it elsewhere, except in Galago pallidas, where there is a trace 

 of such a structure. The glenoid surface is limited posteriorly by a 

 very large and wide postglenoid process, behind which opens a con- 

 spicuous postglenoid foramen. This process is very different in 

 form from that which exists in Lemur; but it is quite like that of 

 Indris, and it also resembles that of Hapalemur and some Galagos. 



There are one or two small suborbital foramina, as in Indris, and 

 the posterior palatine foramina are also small ; but the two genera 

 are distinguished by these latter; for in Indris there is one large 

 posterior palatine foramen behind the last molar, and a small one a 



* In De Blainville's Pgure of the skull of Indris the suture is nearly on a line . 

 with the upper margin of the nasals (see Osteographie, Lemur, pi; 8). 



t Tins process is not represented in De Blainville's figure, but it is in that of 

 Prof. Van der Hoeven. 



Proc. Zool. Soc— 18f>6, No. XI. 



