21() Annals of the Carnegie Museum. 



lateral aspect of the anterior wall of the brain-case, which passes out 

 above between these small prongs of the sphenotic apophysis. For 

 its entire length this excavation is merely separated from the tem- 

 poral fossa of the same side by a line. On this lateral aspect of 

 the skull we are also to observe the unusual dei)th of the orl>ital cavity 

 which is due to the great transverse breadth of the skull ; the com- 

 pleteness of the roof; and the general arrangement of the surrounding 

 bones. 



The interorbital septum is thick and perfectly entire ; the foramen 

 optieiDii circular and small ; while the foramen for the nerve of the first 

 pair is exceedingly minute. Pars plana is almost completely aborted, 

 though the lacrymal bone is of good size. Upon its external aspect, 

 this latter element is flat, its lower free point being broadly rounded, 

 and fails to reach, by quite an interval, the zygomatic bar. It makes 

 an extensive articulation with the frontal by a broad base, and is, near 

 its middle, perforated in the antero-posterior direction by an elliptical 

 foramen. Sometimes this is a deep notch instead, the bone not span- 

 ning it externally. The lacrymal shows also another large foramen 

 higher up, through which nerves and vessels pass to the rhinal cham- 

 ber. The bone is highly pneumatic. 



The zygoma is stout and straight, and somewhat compressed from 

 side to side. It makes a powerful ball and socket joint with the 

 ([uadrate, and at its distal extremity it becomes indistinguishably fused 

 with the nasal and premaxillary. At this point it sends inward a 

 horizontal maxillo-palatine plate of bone, while the mesial portion of 

 this last-named element is of great size and composed of spongy tissue. 

 Together with the maxillo-palatine of the opposite side it nearly fills 

 up the rhinal space. They fuse across the median inter-palatine 

 space with each other, and with most of the bones in the neighbor- 

 hood. This open spongy mass is also carried up to the roof of the 

 rhinal chamber on either side of the narial openings to fuse with the 

 ventral aspects of the nasal in that locality. Posteriorly these masses 

 rise up over and come close to the anterior free edges of the very 

 lofty ascending plates of the palatines to a point about opposite the 

 anterior apex of the sphenoidal rostrum. 



The osseous surface of the under side of the superior mandible is ex- 

 tended well back ; shows numerous foraminal perforations, and its 

 lateral margins for their entire lengths, upon either side, are produced 

 downwards as not very sharp cultrate edges. 



