STUDIES OF THE MA.CIlOCniRES. 



321 



These latter structures will be alluded to again after completing 

 the description o£ a palatine bone. 



The anterior half of a palatine is a narrow ribbon of bone placed 

 horizontally, dilated at its further extremity, which, as has already 

 been said, blends with the horizontal portion of the corresponding 

 premaxillary. The posterior division of the bone feebly develops 

 an inner and an outer carination, the " postero-external " angle 

 being completely rounded off. 



In the median line, beneath the basisphenoidal rostrum, these 

 palatine bones meet each other, and. in front the vomer, for their 

 entire lengths, a union which, in both T. mexicanus and T. pnelJcf, 

 seems to amount to an absolute anchylosis. 



If this prove to be universally the case in the skulls of fully 

 adult Trogons, it need not surprise us, for when we come to the 

 Humming-birds there will be another peculiar anchylosis to be 

 described that is occasionally to be found in their skulls. 



Now the vomer (fig. 8, v.) in both of these Trogons is a rather 

 short subcylindrical rod with a bluntish point. This point rests 

 directly upon the posterior free edge of the osseous nasal septum 

 (n.s.). 



This intimate relationship between the vomer and nasal septum 

 in the Trogons led the late AV. A. Forbes into an error, which will 

 be at once evident upon an examination of his drawing of these 

 parts in Pharomacrus mocinno (P. Z. S. 1881, p. 837). At least 

 it does not hold quite true in the species at hand ; and I suspect 

 that Eorbes, in examining alcoholic specimens, included this thin 

 posterior edge of the nasal septum with the anterior tip of the 

 vomer, giving it that "thin and filiform" appearance to which 

 lie alludes. This slight error might easily be made by that kind 

 of an examination, when in a dried skull, S';ch as I have before 

 me, these parts would be better distinguished. His description, 

 however, in the contribution above referred to, is a marked 

 improvement upon that by Professor Huxley, which it was 

 written to correct ; and the former writer was fully aware of the 

 fact that the nasal septum in the Trogons ossified. In my 

 specimen of T. mexicanus this plate has a large vacuity in its 

 centre, while in T. puella it is entire. 



The lips of the maxillo-palatines do not show in the interpala- 

 tine median space, upon this view of the skull, as they are said 

 to do in P. mocinno by Torbes in the paper just quoted. (Com- 

 pare figure in P. Z. S. 1881, p. 837, and fig. 8 of the present 



