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Show 1903.] OSTEOLOGY OF THE CUCULIFORMES. 279 The furcula lias long, round, slender limbs, gently arched. There is a moderately long and styliform hypocleideum in Geo-coccyx, Coua, Rhamphococcyx, and Piaya, for example. In Crotophaga it is spatulate. In Centropus, Cuculus, Eudynamys, and Cacomantis it appears to be of a degenerate spatulate type; whilst in Scythrops the hypocleideum appears to be wanting. The nature of the combination of the elements forming the inner wall of the foramen triosseum-the acromion of the scapula, the procoracoid, and the free end of the clavicle-may prove, when exhaustively worked out, to have some slight value from a systematic standpoint. I propose, however, here to offer only a few remarks, selecting a few genera as examples. In Cuculus, Scythrops, Coua, the whole free end of the furcula passes up cephalad of the acromion of the scapula and separates the latter from the procoracoid. In Guira, Geococcyx, Rhamphococcyx, Rliinococcyx, Rhopodytes, the acromion turns forwards so as nearly to join the procoracoid, and forms an opposing surface to the free end of the clavicle, which accordingly turns forwards to terminate in a point wedged in between the acromion and procoracoid. Crotophaga resembles Guira in this respect, but the free end of the clavicle is much broader and the articulation with the procoracoid more developed. In Centropus the acromion and acrocoracoid meet and embrace, as in a wedge, the styliform free end of the slender furcula. The procoracoid, which is large, does not come in contact with the scapula. No two of the genera, however, exactly agree, but the differences between them are too slight to be described in words. The coracoid of the Musophagi, though closely resembling that of the Cuculi, is yet readily distinguishable therefrom by the fact that the procoracoid turns downwards and outwards to fuse with the acrocoracoid, thus encircling the foramen triosseum with a continuous bar of bone. The procoracoid is large and passes insensibly backwards into the coracoid shaft, and there is a supracoracoid foramen. The processus lateralis is well developed, and directed outwards and upwards into a point. In the region where the pro- and acrocoracoid fuse there is an elongated facet for the articulation of the furcula. The procoracoid, however, appears to take the greater part of the share in furnishing this surface. On the dorsal or internal aspect of the coracoid there is developed a special articular surface for the dorsal lip of the coracoid groove of the sternum. The furcida has relatively shorter, broader, and more laterally compressed limbs than in the Cuculi. A hypocleideum is wanting. The dorsal extremity bears a special projecting facet for articulation with the procoracoid. The scapida resembles that of the Cuculi, but is relatively slightly broader and has a large acromial process. The pro- and acrocoracoid meet and fuse one with the other, thus excluding the furcula from participation in the formation of the foramen triosseum. |
