OCR Text |
Show 278 MR. W. P. PYCRAFT OX THE [Mar. 17, posteriorly than in Schizorhis. The sternal notches of Turacus, it is to be noted, though preserving the same relative proportions between themselves, are yet relatively shallower than in Schizo-rhis with regard to their relation to the corpus sterni. There is a well-developed spina externa, but no trace of a spina interna. In Schizorhis the spina is flabellate and projects from a rounded base. In Turacus it is quadrate in form. In T. buffoni it projects nearly as far forwards as the antero-ventral angle of the carina, and is distinguishable from the anterior border of the carina only through the medium of a notch. Were this notch filled up, the spina would disappear and the anterior border of the keel would present a vertical face projecting far beyond the coracoid grooves, as in certain Coraciiform birds, e. g. Cyanops. The coracoid grooves overlap one another. The dorsal lip is extensive. A median notch occupies the place of the spina interna, and this is bounded on either side by a conspicuous oblong glenoid surface, which articulates with a special facet 011 the coracoid. In the Cuckoos the dorsal up does not overhang the ventral, the coracoid grooves do not overlap nor in some cases even reach the middle line, and the oblong articular facet on the dorsal lip for articulation of the coracoid is only slightly developed. In the Musophagi the dorsal surface of the base of the spina externa affords articulation for the right coracoid; in the Cuckoos this is never the case. In the Musophagi the articular surfaces for the ribs are fairly widely spaced, less so in Turacus; in the Cuckoos these surfaces are crowded together. The coracoid in the Cuculi is relatively long and slender, being nearly or quite as long as the sternum. From the ventral aspect, one of the most conspicuous features is the large procoracoid. This forms a large oblong shelf projecting inwards and downwards from the shaft, at about the level of a line drawn across the shaft from behind the glenoid cavity. The acrocoracoid is large, and not twisted 011 the shaft so as to conceal the foramen interosseum. The processus lateralis is well developed and the foramen supra-coracoideum is absent. The p>rocessus lateralis basalis may be either broad and quadrate, with its antero-external angle produced forwards into a spine, as in Cuculus, Rhopodytes, Eudynamys, Taccocoua, Rham-phococcyx, Scythrops, and Guira; or narrow and directed outwards and backwards, as in Centropus, Coua, and Dromococcyx. I11 Taccocoua, and to a less marked extent in Centropus, the impression for the sterno-coracoideus muscle, on the dorsal aspect of the coracoid, is bounded in front by a sharp vertically directed spine. The scapula is long and narrow, and differs somewhat in shape in the different genera; but the variations are unimportant, and not sufficiently large to justify description here. The acromion is short and stout, save in Coua reynaudi, wherein it is reduced in width to form a somewhat cylindrical process. |