Proceedings of the Scientific Meetings of the Zoological Society of London 1867

Page 296

1867.] MR. ST. GEORGE MIVART ON INDRIS DIADEMA. 253 the fronto-maxillary suture being a little anterior to their posterior termination. As in the other Lndrisince, there is no malar foramen, and the lachrymal opening is very near the margin of the orbit. The floor of this latter part (the orbit) is not so large relatively as in 7. laniger; but, as in that species, it is placed lower down than in 7. brevicaudatus, so as to be but little above the alveolar margin of the upper jaw. The malar is wide and extends back very nearly to the glenoid surface ; but its lower part does not offer a vertically ridged and grooved space for the attachment of the masseter (though such may very probably be developed with age), neither is there any process given off from its posterior border above the zygomatic process of the squamosal. The glenoid surface and the post-glenoid process and foramen are all as in the other Lndrisince. There are two small suborbital foramina; and the posterior pala­tine foramina are also small, and are intermediate, as to their deve­lopment, between the conditions presented by 7. laniger and 7. brevi­caudatus respectively ; for the foramen behind the last molar and the two in front of the posterior margin of the palate are all of moderate size. The anterior palatine foramina are rather large, and the palate is much as in 7. brevicaudatus, except that its posterior border is scarcely at all thickened. The most anterior point of its posterior border is in a line with the anterior margin of the last molar. There is a small but distinct paroccipital process, and much smaller than that of the last-named species ; but in the union of the foramen rotundum with the sphenoidal fissure, the conspicuous Vidian fora­men, and the other points before mentioned* in describing 7. laniger, 7. diadema agrees with both the other species of Lndrisince. I am unable to say, however, whether there is or is not a crista galii. A very large and conspicuous stylo-mastoid foramen opens imme­diately behind and beneath the aperture of the meatus auditorius externus. In the form of the mandible, 7. diadema presents an interesting intermediate condition between 7. brevicaudatus and 7. laniger, the posterior part of the articular surface of the condyle being much flattened, but not vertically grooved, and the digastric fossa and ridge above the mylohyoid foramen being more marked than in the former species, but not so much so as in the latter one. The bend­ing downwards of the angle of the mandible is also intermediate. Dimensions. . , inch. Length from anterior end of the praemaxilla to an­terior margin of the foramen magnum 2*35 Length from anterior end of prsemaxilla to most an­terior point of orbital margin 0*65 * P. Z. S. 1866, p. 162.