OCR Text |
Show 40 MR. W. P. PYCRAFT ON THE [May 2, should rather be described as blade-shaped, the dorsal edge of the blade being much thickened ; in other words, the ventrally p acec keel of the triangle seen in Corydon has in this genus extended downwards. The median line of the dorsal surface of the corpus sterni is deeply grooved, and pierced anteriorly by a laige pneumatic foramen. In Cymbirhynchus, and to a less extent in Calyptomena, the groove is laced across by narrow, irregulai bars of bone. The carina is deep, and has the free (ventral) edge produced forwards. The anterior (vertical) border bears a hollow groove for the reception of the hypocleideum. The coracoid grooves look directly forwards, and do not meet in the middle line. The dorsal lips are prominent and thickened ; the ventral lips are well-defined, but have knife-like edges continued inwards on to the spina externa. Text-fig. 13. Sternum of Calyptomena, showing the simple (unbifurcated) spina externa, s.e. a.i.p., anterior lateral process; c., carina; p.l.p., posterior lateral process. The coracoids are long ; as long as, or longer than, the corpus sterni. The procoracoid process, though reduced, is still moderately large, and forms a narrow flange of bone, arising beyond the middle of the coracoid shaft and having its free edge directed downwards. Cephalad it articulates with the scapula, and with the clavicle forms the foramen triosseum. The procoracoid of the Eurylsemidse is larger than in the Cotingidse. In the Picidie the procoracoid appears to be wanting, and in the higher Passeres it is reduced to the merest vestige, e. g. Corvus. The breadth of the base of the coracoid is increased by narrow phalanges of bone, one on either side extending forwards, for about one-fourth the length of the shaft. On the dorsal aspect of the shaft a prominent tongue of bone is sent up to abut against the dorsal lip of the coracoid groove. This at least obtains in Calyptomena ; in Corydon and Cymbirhynchus it is less marked. The scapida is long, narrow, and scimitar-shaped. The farcula |