1905. | OSTEOLOGY OF THE EURYLEMIDE. 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 Chasmorhynchus. In the latter, 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 Cymbirhynchus these processes are more 
slender than in Calyptomena. In Cymbirhynchus they are hook- 
shaped. 
Probably, as I have remarked, the maxillo-palatines of 
Calypiomena at an earlier stage closely resembled those of 
Chasmorhynchus. It seems also highly probable that these, in 
turn, were derived from yet more primitive and much more 
extensive triangular plates such as have been retained by the 
‘Tyrannide. The palate of Vityra, indeed, shows how easily the 
Eurylemiform palate could have obtained its peculiar maxillo- 
palatines. 
The quadrato-jugal bar in Calyptomena as in Chasmorhynchus 
is sigmoidally curved, as much so as in some Spheniscide. In 
Corydon and Cymbirhynchus it is straight. There are no separate 
elements distinguishable in this bar. 
The Vomer, Palatines, and Pterygords. 
The vomer (Pl. 11. fig. 2a), in Calyptomena, is roughly oar- 
shaped in front and terminates caudad in a pair of long, slender 
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 was earlier of a more pronounced Aigithognathous 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 truncate with prominently 
produced angles. The dorsal aspect of the vomer is closely applied 
to the base of the septum nasi. 
Oymbirhynchus resembles Corydon in the shape of the vomer, 
but differs therefrom in that it is slightly constricted between the 
free end and the origin of the posterior cornue, which fuse com- 
pletely with the palatines, forcing the parasphenoidal plates thereof 
away from their normal relationship to the parasphenoid. 
In the Coraciidee the vomer is either wanting or reduced to a 
mere spicule, e. g. Hurystomus. 
In Chasmorhynchus the vomer is larger than in the Kurylemide. 
Aigithognathous anteriorly, it terminates posteriorly ma a pair of 
