1867.] MR. ST. GEORGK MIVART ON INDRIS DIADEM A. 2f>3 



the fronto-maxillary suture being a little anterior to their posterior 

 termination. 



As in the other Lidrisince, 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 I. laniyer ; but, as in that species, it is placed lower down than 

 in /. 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 IndrisincB. 



There are two small suborbital foramina ; and the posterior pala- 

 tine foramina are also small, and are intermediate, as to their deve- 

 lopment, between the conditions presented by I. laniger and /. brevi- 

 caudatus 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 I. 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 fora- 

 men, and the other points before mentioned* in describing /. 

 laniger, I. diudema agrees with both the other species of Indrisinee. 

 I am unable to say, however, whether there is or is not a crista 

 gain. 



A very large and conspicuous stylo-mastoid foramen opens imme- 

 diately behind and beneath the aperture of the meatus auditorius 

 externus. 



In the form of the mandible, /. diadema presents an interesting 

 intermediate condition between /, brevicaudatus and /. 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 bend- 

 ing downwards of the angle of the mandible is also intermediate. 



Dimensions. . , 



inch. 



Length from anterior end of the praemaxilla to an- 

 terior margin of the foramen magnum 2*35 



Length from anterior end of praemaxilla to most an- 

 terior point of orbital margin 0'65 



* P. Z. S. 1866, p. 162. 



