1885.] TROCHILID^, CAPRIMULGID^, AND CYPSEUD^. 889 



end. Quite a prominent peg-like process is developed to receive 

 the excavated end of the corresponding pterygoid. The " orbital 

 process " is much reduced and inconspicuous, and the entire bone is 

 thoroughly pneumatic. 



Many points of uncommon interest present themselves for our 

 examination upon the under vievr of the skull of Trochilus. They 

 are all clearly shown in my drawing of these parts (Plate LVIII. 

 fig. 3). Anteriorly, we observe, underlying the lateral margins of the 

 premaxillary, its slender and free dentary processes, each fusing 

 behind with a similarly delicate rod of bone sent forward on the part 

 of either maxillary (Pmx). 



We find that this last-named element developes a broad maxillo- 

 palatiue process, which latter portion is carried far forward as a free 

 lamella of bone with pointed apex, while the maxillary proper becomes 

 continuous with the dentary rod of the premaxillary in the method 

 already described. 



A wide interval separates, in the median space, the maxillo-pala- 

 tines (Mxp), within which the vomer ( Vo) is plainly to be seen. 

 This last bone is deeply cleft behind, where it rides the very large 

 rostrum, while anteriorly it is produced as the finest imaginable 

 spiculi-form prolon;iation '. The posterior vomerine limbs are above 

 the palatines, each one extending backwards nearly to the pterygoidal 

 articulation on either side. Adopting the admirable nomenclature 

 for the different parts of the jjulatine bone proposed by Prof. Iluxley, 

 we find that the body of the bone, being flat and horizontal, lacks 

 the prom.inent internal and external lamince found in many birds, its 

 outer margin being produced forwards as a very narrow strip of 

 bone to underlap the maxillo-palatine of the same side, and iiulistin- 

 guishably fused with it, at a point about opposite the anterior apex 

 of the vomer. The inner palatine margin, for its anterior moiety, is 

 produced forwards as a free apophysis shutting out from our sight, 

 upon this aspect of the skull, the corresponding vomerine limb. 

 This latter is applied to the "ascending process," the inner margin 

 of which is that part of the palatine bone which rests against the 

 sphenoidal rostrum. The "postero-externalanffle" is, in Trochilus, 

 reduced to nil, as already hinted ; the outer margin of the palatine is, 

 from head to anterior ending, nearly a straight line. 



A considerable interval exists between the palatines in the middle 

 space, and, indeed, these bones do not come in contact with each 

 other anywhere throughout their extent. 



Posteriorly, the palatine head articulates with the pterygoid in a little 

 pit that occupies the summit of a well-marked elevation developed on 

 the part of the rostrum beneath the point of meeting of these elements. 



1 Professor Huxley states, in^his " Classification of Birds " (P. Z. S. Api-il 11th, 

 1867), that " Trochilus has the true Passerine vomer, with its broad and trun- 

 cated anterior, and deeply cleft posterior end. I have not yet been able to 

 obtain a perfectly satisfactory yiew of the structure and arrangement of the 

 palatine bones in the Humming-birds." I must believe from the statement 

 made in the latter half of the quoted paragraph that the skull in Prof. Huxley's 

 hands was an imperfect one, and that the delicate vomer I have described above 

 was broken off, leaving only the broad base referred to by him. 



