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Show 904 DR. R. W. SHUFELDT ON THE OSTEOLOGY OF THE [Dec. i, The transverse processes of the tail-vertebrae in Chordediles are very long, and though the neural spines are not lofty, the last four segments have prominent bifid hypapophyses, which are not nearly so conspicuous in the Whippoorwill. Notwithstanding the fact that the pelvis has the same general characters alike in these two genera, there are at the same time a number of striking minor differences which render it impossible to mistake their identity. In both forms the bone is notably spread out and flattened in the vertical direction ; this is perhaps best marked in the Nightjars, where, too, we find the ilio-neural grooves shallow and wide, and the anterior or preacetabular portion of the ilium long and narrow, being concaved for its entire length. The parial foramina on the hinder moiety of the dorsal aspect are large, regularly decreasing in size as we pass forwards. Upon this view the tops of the anti-trochanters form a prominent lateral feature of the pelvis. Regarding the bone upon side view in C. texensis, we observe . that the outer marginal line of the ilium is directly continuous with the postpubis behind, the propubis being entirely absent. The postpubic element is extremely slender, and in direct contact with the inferior margin of the ischium for its entire length, projecting but a short distance beyond it behind. The obturator foramen is relatively very small, and, indeed, neither the acetabulum nor the ischiac foramen is of great size comparatively. P. nuttalli has a proportionately deeper and narrower pelvis than the one just described for a Night-hawk, with its ridges and lines more pronounced, giving tbe bone a more angular aspect. The ilia in front have their anterior ends drawn out into points, and turned in nearly to touch the quite prominent crista formed by the common neural spines of the sacral vertehrae. This feature is characteristic of the pelvis in the Whippoorwill, and at once distinguishes it from the pelvis in the other genus. Plate LXI. fig. 2 shows very well the general form of the sternum and the shoulder-girdle in the Caprimulgida, and their mutual relation when articulated in situ, the specimen being from C. texensis. It will be seen that the sternum is broadly 1-notched at its posterior border; that it is without a manubrium, and has a concave anterior, and convex inferior border to its handsome keel, the angle at the meeting cf the two being rounded off. The costal processes are well pronounced (still more so in P. nuttalli), and the sternal body is decidedly concave on its dorsal aspect, usually showing a median pneumatic foramen in front. A coracoid has a subcylindrical shaft of considerable length, terminated above in a tuberous summit, and a well-dilated sternal extremity with upturned external process. These bones, when articulated, do not meet in the median line. The furcula assumes the U-shaped pattern of the bone, with but a fairly-well developed hypocleidium. Its limbs are transversely compressed, and the terminal head not much dilated. These latter rest, when in situ, |