1905.] OSTEOLOGY OF THE EUEYLtEMID^, 39 



corresponding to the sub- crescent ic plates of Calyptomena. These 

 hemipterygoids, in both the Euryloemid and Cotingid forms, 

 articulate with the palatines, in the adult, by means of an oblique 

 suture. 



Corydon and Cymhirhynchus differ in no essential features from 

 Calyptomena. 



The quadrate is peculiar in that, in common with the Tyrannidse 

 and some other Passei^ine forms, it sends out a strong spur for the 

 articulation of the quadrato-jugal bar. This spur projects like a 

 buttress laterad of the outer condyle for the lower jaw. The 

 squamosal and otic heads are closely approximated. The former 

 is wedged in between a prominent -processus articidaris squamosi 

 behind, and an equally well- developed processus articularis zygo- 

 maticus in front. In Corydon these processes are expanded 

 laterally so as to overhang the head of the quadrate, but at the 

 same time they afford this element a greater freedom of movement 

 than in Calyptomena. Cymhirhynchus and Utorylcemus are inter- 

 mediate in character in this respect. 



The Mandible. 



The mandible, in the Euryhemidas, is much bowed outwards 

 to a very considerable extent. In Calyptomena it has only a 

 relatively small symphysis : is truncated posteriorly, and shows 

 little or no trace of the separate elements of which it is composed. 

 The internal angular process is moderately well developed, and is 

 perforated by a small pneumatic foramen. The rami, in their 

 general shape, are rod-like, and slightly compressed laterally. 



In Corydon and Cymhirhynchus, however, there is an abrupt 

 ti'ansition between the malar region of the mandible and that 

 portion covered by the rhamphotheca, which is most markedly 

 thicker and broader than the hinder region. The symphysial 

 region is very broad and spoon-shaped. The internal angular 

 process is more spine-like than in Calyptomena^ and there is a 

 feebly- developed posterior angular process. 



The Hyoid. 



The hyoid of the Eurylaamidte resembles fliat of the higher 

 Passeres. The basihyal (os entogiossum) is made up of a pair of 

 boomerang-shaped ossifications placed dos a dos, so that a long 

 free process is produced backward beyond the articulation with 

 the basibranchial 1. Basibranchials 1-2 are fused; the latter, 

 however, is a long cartilaginous style. The ceratobranchial and 

 epibranchials are of moderate length ; the latter are cartilaginous 

 at the free ends. 



In Corvus, for example, among the higher Passeres, the basi- 

 hyals are long and straight, and run parallel with one another, 

 yet so as to leave a median space between them. 



