1905.] OSTEOLOGY OF THE EURYL/EMIDiE. 37 



side of the skull, terminate immediately beneath the free end of 

 the vomer. 



That these processes are degenerate there can be no doubt. 

 They have probably been derived from a condition precisely 

 similar to what obtains in Chasmo7^hynchus. In the lattei-, these 

 processes are swollen and spongy in character. Arising from the 

 maxilla at a point almost immediately below the descending 

 process of the nasal (in Calyptomena they arise distad of this 

 point), they extend backwards so as to run on either side of and 

 beneath the vomer for nearly one-fourth of its length. 



In Corydon and Gymhirhynclitis these processes are more 

 slender than in Calyptomena, In Gymhirhynchus they are hook- 

 shaped. 



Probably, as I have remarked, the maxillo-palatines of 

 Calyptomena at an earlier stage closely resembled those of 

 Ghasmorhynchus. It seems also highly probable that these, in 

 turn, were derived from yet more piimitive and much more 

 extensive tiianguk^r plates such as have been retained by the 

 Tyrannida3. The palate of Titijra, indeed, shows how easily the 

 Eurylsemiform palate could have obtained its peculiar maxillo- 

 palatines. 



The quadrato-jugal bar in Galypiomena as in Ghasmorhynchus 

 is sigmoidally curved, as much so as in some Spheniscidfe. In 

 Gorydon and Gymhirhyncluis it is straight. There are no separate 

 elements distinguishable in this bar. 



The Voiner, Palatines, and Pterygoids. 



The vomer (PI. II. fig. 2 a), in Galyptomena, is roughly oar- 

 shaped in front and terminates caudad in a pair of long, slendei' 

 limbs, bowed outwardly so as to enclose a space through which the 

 parasphenoidal rostrum may be seen, and fused completely with 

 the palatines. The free end of the blade is truncated, and has the 

 angles produced into minute processes, thus showing that the 

 vomer Avas earlier of a more pronounced ^githognathous type. 



In Corydon the vomer is much reduced, being represented by a 

 short, broad, oblong body produced caudad into a pair of widely 

 separated and slender rods which articulate with the palatines. 

 The free end of the vomer is squarely trvnacate with pi'ominently 

 produced angles. The dorsal aspect of the vomei' is closely applied 

 to the base of the septimn nasi. 



Gymhii'hynchus resembles Gorydon in the shape of the vomer, 

 but difi'ers therefrom in that it is slightly constricted between the 

 free end and the origin of the posterior cornuae, which fuse com- 

 pletely with the palatines, forcing the parasphenoidal plates thereof 

 away fi'om their normal relationship to the parasphenoid. 



In the Coraciidae the vomer is either wanting oi' reduced to a 

 mere spicule, e. g. Eurystomus. 



In Ghasmorhynchus the vomer is lai'ger than in the Euryleemidje. 

 ^githognathous anteriox-ly, it terminates postei'iorly in a pair of 



