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Show 1866.] MR. ST. GEORGE MIVART ON MICRORHYNCHUS. 161 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 Lemuridar, 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 Blainville's 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 irregular, forming a vertically ridged and grooved surface for the attachment of the masseter, which surface is bounded above by an anteroposterior^ directed ridge. The malar also developes, from its posterior border, an obtuse process^ (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 Lemuroid. 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 this Lemuroid to differ strikingly in aspect from that of any other member of the suborder. %r The glenoid surface for the lower jaw is strongly concave from within outwards and faintly convex from behind forwards at its anterior 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 pallidus, 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 conspicuous 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 D e Blainville's figure 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 This process is not represented in D e Blainville's figure, but it is in that of Prof. Van der Hoeven. PROC. ZOOL. Soc-1866, No. XI. |
