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Show 1905.j OSTEOLOGY OF THE EURYL^EMID^E. 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 liook-shaped. Probably, as I have remarked, the maxillo-palatines of Calyptomena 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 Tyrannidse. The palate of Tiiyra, indeed, shows how easily the Eurylsemiform 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 Spheniscidte. In Corydon and Cymbirhynchus it is straight. There are no separate elements distinguishable in this bar. The Vomer, Palatines, and Pterygoids. The vomer (PI. II. fig. 2 a), in Calyptomena, is roughly oarshaped 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 ^Egithognatlious 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. Cymbirhynchus 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 cornuse, which fuse completely with the palatines, forcing the parasphenoidal plates thereof away from their normal relationship to the parasphenoid. In the Coraciidse the vomer is either wanting or reduced to a mere spicule, e. g. Eurystomus. In Chasmorhynchus the vomer is larger than in the Eurylsemidas. vEgithognathous anteriorly, it terminates posteriorly in a pair of |