62 Annals of the Carnegie Museum. 



turl)inated bones, although at least two on either side are well de- 

 veloped both in L. griseoviridis and in the marmoset. There are in 

 these apes no supia-orbital ridges beyond the ones formed by the 

 superior peripheries of the orbits, as we find in most human skulls, 

 even among the lower races of men, where such ridges aie present on 

 the frontal bone above the orbits. These latter are sometimes absent 

 in negioes of pure strain. 



With regard to the lateral aspect of these skulls (PI. XIII, figs. 3 

 and 4; PI. XVT, fig. 10) it may be observed that in all of them the 

 extent of the cranial capacity is far greater than might be inferred 

 from the facial view alone. This is especiallj^ true in the case of the 

 marmosets and L. callitrichus. In L. griseoviridis the cranial dome 

 is more depressed anteriorly. In C. jacchiis and in L. griseoviridis 

 the superior bordei of the zygoma is produced backward and upward, 

 to be lost as a prominent ridge on the lamboidal suture. This feature 

 is best seen in L. griseoviridis, and is wholly absent in L. callitrichus. 

 As in man, the temporal fossa is deepest opposite the middle third of 

 the zygoma, while anteriorly the space is occupied by the outward 

 bulging of the external wall of the corresponding orbit, especially in 

 C.jacchus. 



The zygoma is nearly horizontal, presenting a gentle sigmoid curve, 

 with the tubercle at its posterior extremity very much aborted, prac- 

 tically absent in C. jacchiis and L. callitrichus. The mastoid process, 

 likewise, does not constitute a prominent feature in these skulls, and 

 is only faintly indicated in the marmoset, in which conspicuous 

 auditory bullae are developed, a character which is entirely absent 

 in Lasiopyga. The mastoid foramen is above the aural opening in C. 

 jacchus, while it is found posterior to it, and at the base of the skull, 

 in Lasiopyga ( Cf. PI. XV, fig. 7, to the right). Extensive, shallow, and 

 flat, the glenoid fossa is hardly deserving of the name, and it is only 

 in L. callitrichus that it presents any concavity at all. However, the 

 post-glenoid apophysis is strong and pointed in all of these apes, and 

 materially contributes to the articulatory surface for the mandible 

 and to keeping it in place. 



Apparently absent in C. jacchus, the styloid process is ver^' small 

 in L. callitr'chus, though better developed in L. griseoviridis. 



In the temporal fossa, the wing of the sphenoid always appears to 

 articulate by suture with the parietal of the same side. This fact is 

 mentioned for the reason that Owen, in his Anatomy of Vertebrates 



