MORPHOLOGY OF OPISTHOCOMUS CRISTATUS. 55 



The pterygoids {pg.)axe also simple, with scarcely aay epipterygoid process, and with 

 the articular plate for the basipterygoid spur far back as in the Tinamou and Ostrich. 

 That this bird is not a special Gallinaceous form is also seen in the fact that the front 

 part of the pterygoid does not remain on that bone and become specialized as a 

 particular peg as in all true Fowls, but becomes segmented off, as in Tinamous and 

 most Carinatse, to form a mesopterygoid, which, however, as in the Carinatee generally, 

 soon fuses with the palatine. These bones meet right and left, and hide the rostrum 

 of the sphenoid as in most birds. As we pass from the most special kinds of modern 

 Fowl to the older types the vomer is seen to become larger, as in the Talegalla ; but 

 it is always azygous. The vomer {v.) in this bird is large ; in the 1st stage it reaches 

 halfway from the ascending plates of the palatines to the end of the intertrabecula 

 (PI. VIII. fig. 1); the hinder pointed end just wedges in between these two plates; 

 its fore end is thick and bifid. The enlarged split fore end in all three stages is such 

 as to suggest that this was formed at first, for a day or so, of two club-shaped centres 

 of bone, and not of a single thread, as in the Gallinaceous types generally. This is 

 another generalized character, for in most birds that have a large or a wide vomer it is 

 double at first ; but it is single in those in which it is a mere vertical plate or a narrow 

 median needle ; when double, the fusion takes place very early as a rule. Behind the 

 palate, but on a higher plane, we see the triple bony tract that forms the parosteal 

 support of the endocranium. This tract, the parasphenoid, was, as the early stage of 

 the Fowl shows (Phil. Trans. 1869, pi. 80. fig. 2, h.t.), composed of a pair of centres 

 under the skull-bowl — these are the basitemporals ; and of a median bar, the rostral 

 part, which supports the thick trabecular base of the interorbital septum. These 

 parts are so generalized that they come in character exactly between those of the 

 Carinatse and of the Eatitse, The rostrum is nearly Struthious in respect of the 

 backward position of the basipterygoids, and the temporary cartilaginous core of each 

 process was evidently a direct outgrowth from the basis crauii, and not a mere 

 articular tablet of cartilage developed afterwards, as in the Common Chick (Phil. 

 Trans. 1869, pi. 83. figs. 1, 13, 14). The basitemporals {b.t) are larger than in the 

 Struthionidse, and smaller by far than in Fowls and Geese ; they are, indeed, very 

 similar to what we find in birds generally ; they are generalized, and not specially 

 Gallinaceous. 



osseous fishes, are mere ossa mystacea. Indeed, the palatine part or maxillo-palatine process {mx.p.) is less 

 developed than even in typical Fowls and Hemipods, scarcely more than in the Pioidfe, quite unlike what is 

 seen in the Musophagidse, or even in the large Cracidae, for these latter have secondary Desmognathism. This 

 bird is as Schizognathous as a Lizard ; it is " Saurognathous." The cheek-splints, jugal and quadrato-jugal 

 (_/., q.j.), are rather feeble, but normal ; the submedial bars, the palatines {pa.), and the pterygoids {pg.) are of 

 the simplest kind ; the former have no postero-external angle, scarcely any groove in the hind part, but have 

 an extensive ascending plate. 



