320 



DE. E. W. SHUFELDt's MOEPHOLOGTCAL 



is this true of the superior vacuity. In botli of these Trogons, 

 however, although these foramina are very large, they still retain 

 their individuality, and do not merge with each other. 



At the upper part of the interorbital septum we observe, 

 plainly marked, the track for the first pair of nerves. It does 

 not in either of these specimens communicate, through a thinning 

 of the walls, \^ith a similar track in the opposite orbital cavity, 

 as we often see in other birds. 



Anteriorly the partition between the orbit and rhinal chamber 

 is composed of an exceedingly small pars plana, and of a thin 

 membrane which stretches from it to the already-described lacry- 

 mal bone. In the dried skeleton, after the membrane has been 

 removed, the communication between these two cavities is un- 

 usually free, more so than in any other bird that I happen to 

 recall at the moment. The periphery of the orbit is sharp for 

 its anterior two thirds, but becomes rounded otf as it passes 

 backwards over the anterior wall of the brain-case in line with 

 the lateral processes of the skull. 



Sutural traces among the original elements composing the 

 quadrato-jugal bar are hardly perceptible, and this osseous rod is 

 quite straight from one end to the other, its tip only being bent 

 up as it articulates with the quadrate. 



Each nasal bone, in this skull, has completely merged with the 

 premaxillary and frontal of the same side, so that all traces of its 

 original borders are obliterated, and it has become thoroughly 

 incorporated in the conformation of the osseous superior mandible. 



We Avill now turn to the underside of the skull of Tro(jon mexi- 

 canus, where we find many points of interest presented for exami- 

 nation. Approximately speaking, the majority of structures 

 observable upon this aspect are Ibund in the same horizontal 

 plane, which plane nearly includes the entire foramen magnum, 

 and the anterior moiety of this opening may be said to lie 

 in it. 



The roof of the anterior half of the mouth is composed of a 

 continuous plate of bone contributed by that portion of the pre- 

 maxillaries. Into the hinder border of this plate we find the 

 anterior and dilated ends of tlie palatines merging. At tliis 

 point these latter bones are quite close together ; posterior to it, 

 however, an oval, longitudinal interpalatine space occurs through 

 which we can see the osseous nasal septum and the vomer. 



