004 DR. R. \V. SHUFELDT ON THE OSTEOLOGY OF THE [DeC. i, 



Tlie transverse processes of the tail-vertebrse in Chordediles are 

 very long, and though the neural spines are not lofty, the last four 

 segments have prominent bitiJ hypapophyses, which are not nearly 

 so conspicuous in the Wliippoorwill. 



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 diiferences which render it impossible to 

 mistake their identity. 



In both forms the bone is notably spi'ead 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 tor its entire length, pro- 

 jecting but a short distance beyond it behind. 



Tlie obturator foramen is relatively' very small, and, indeed, 

 neither the acetabulum nor the ischiac foramen is of great size 

 comparatively. 



P. mittalli has a proportionately deeper and narrower pelvis than 

 the one just described for a Night-hawk, with its ridges and lines 

 more pronounced, giving the bone a more angular aspect. 



The ilia in front have their anterior ends drawn out into points, 

 and turned in nearly to touch the cjuite prominent crista turmed by 

 the common neural spines of the sacral vertebrae. 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 Caprimulyidce, and their mutnal re- 

 lation when articulated in situ, the specimen being from C. texensis. 

 It will be seen that the sternum is broadly 1 -notched at its poste- 

 rior border ; that it is without a manubrium, and bas a concave 

 anterior, and convex inferior border to its handsome keel, the angle 

 at the meeting of the two being rounded off. 



The costal processes are well pronounced (still more so in P. nut- 

 talli), 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, wb.en articu- 

 lated, 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 ter- 

 minal head not much dilated. These latter rest, when in situ. 



