54 ANATOMY 01- VERTEBRATES, 



suture in Struthio, where they are wide apart, and j^ass ahnost 

 parallel backward to join the pterapophyses of the basisphenoid 

 and the tympanies ; developing a broad plate mesially to abut 

 upon the presphenoid : their palatine ends are nearer each other, 

 and their course to the tympanies more divergent, in the Emeu, 

 Apteryx, Hemipode : they touch each other anteriorly in some 

 birds ; and, in a few {Podicejjs, Sula, Ibis, Argala, Scolopax), 

 have a short extent of mutual junction before diverging. In 

 Rliea the fore part of the pterygoid is slender, is attached to the 

 vomer and presphenoid, traverses obliquely the upper surface of 

 the palatine plate, with which it ultimately coalesces, and becomes 

 engrained between the pterapophysis and orbital process of the 

 tympanic before abutting upon the inner and lower condyle of 

 that bone. In general the pterygoids are straight and slender; 

 they diverge at an open angle in Rajytores, at an acute angle in 

 Colymhiis, are nearly parallel and longitudinal in Struthio, with 

 intermediate relative positions in other birds. In Raptores their 

 connections are limited to the essential terminal ones with the 

 palatines and tympanies : in some other birds they articulate, 

 occasionally by a distinct process, with pterapophysial extensions 

 of the basisphenoid, limiting the movement of the tympanic, and 

 adding strength and fixity to the upper mandible : in most birds 

 there is a prominence or process from the hinder border for liga- 

 mentous attachment to the basisphenoid. In Rhea there is an 

 articular process for the orbital plate of the tympanic. The 

 tympanic joint is double in Pheasants and Plovers. 



The bone, figs. 28-32, 26, answering to that so numbered in 

 figs. 91, 92, 93, 95, vol. i., is a straight, slender, usually triedral, 

 style in birds, articulating with 20 by one end and mth 27 by the 

 other, and in some birds being joined by a descending process 

 from the lacrymal. It combines all the essential homological 

 characters of the ' malar,' those, viz., derived from relative position 

 and connections ; and exemplifies the unimportance of configura- 

 tion : showing the opposite extreme to the scale-like shape of the 

 bone in the Turtle, fig. 91, 26, vol. i. The malar of the Crocodile, 

 fig. 95, 26, offers an intermediate modification of form. The 

 malar in the bird overlaps the maxillary by an oblique suture, as 

 in the Keptiles. 



The zygomatic connection between the maxillary and tympanic 

 is completed by the bone, figs. 28-32, 27, which has the same 

 slender figure as 26, with Avhich it early coalesces ; but preserves 

 a moveable articulation with 28 by a convex condyle adapted to 

 the acetabulum on the outer side of the tympanic. The two 



