OCR Text |
Show 1885.] TROCHIL1D.E, CAPRI M ULGI D.E, AND CYPSEL1D.E. 903 The bone is notably compressed in the vertical direction from head to apex, the former being unusually flattened for a representative of this class. Rather more than the hinder third of the blade is bent abruptly in such a manner as to have the angle occur on the inner margin, with its aperture, quite an open one, to the outer side. From this point to the sharp apex, the blade gradually tapers away. When this pectoral arch is articulated the axis of the shaft of the coracoid is approximately in a plane which is parallel to the plane of the dorsal surface of the sternal body. Of the remainder of the Axial Skeleton in certain Caprimulgine Birds.--Nuttall's Whippoorwill and Chordediles each have eleven vertebrae in their cervical region before we come to a segment supporting a free pair of ribs. Each agrees, again, in having this first pair of ribs rather long and without epipleural appendages. In the Whippoorwill the next pair of ribs also have free extremities and well-developed processes anchylosed to them, while in the Nightjar, these latter also being present, we find that the ends of the ribs. articulate with sternal ribs. These are of unusual type in a specimen before me, being high up on the costal processes, exceedingly small, indeed far smaller than I ever saw them in a bird of the same size, and the one on the left side being anchylosed to the sternum. Posterior to this pair of ribs both of these forms agree again, and that in having four more pairs each. Of these, the first three fulfil all the requirements of true dorsal ribs as we find them among birds generally. The last pair spring from the sacrum, although their haemapophyses also reach the costal borders of the sternum. They do not have epipleural appendages upon them. It will be seen that this arrangement gives the Goatsuckers 16 movable vertebrae in the column before arriving at the first one appropriated by the pelvis. Then, as well as I can manage to count in the adult specimens, either of these birds has ten more segments in the pelvic sacrum. Chordediles differs from the Whippoorwills, however, in having six caudal vertebrae and a pygostyle, whereas the latter have but five and the terminal piece. In either genus the pygostyle has a long, sharp, and straight superior border, and a thickened posterior one, especially below where a triangular flattened area makes its appearance, and the bone is not nearly so deep in the antero-posterior direction. With the exception of the tuberous apophysis of the axis, the vertebrae in these birds are notable for the entire absence of the neural spines until we find them developed in the dorsal series. On the other hand, after passing the four or five vertebrae in the mid-cervical region that are marked by the open carotid canal, the hyp-apophyses are quite a prominent feature, and it is only in the last two segments before the pelvis that these latter are absent. The lateral canals commence in the third vertebrae and extend through the cervical series as usual. |