350 
DR. R. W. SHUFELDT’S MORPHOLOGICAL 
whereas in the specimen of the Whip-poor-will before me they 
are quite rudimentary and small, although they have both head 
and tubercle. 
For the rest of the vertebral column in these two birds, they 
practically agree, both in number and arrangement of the ribs and 
vertebrse. Their pelves are also very much alike, and wear the 
same pattern for general outline, even to the pointed and in-turned 
anterior tips of the ilia, which latter feature constitutes a very 
excellent character for this bone, at once distinguishing it from 
the pelvis of a Chordeiles. 
Antrostomus also agrees with the Poor-will in having but Jive 
free vertebrae and a pygostyle in the skeleton of its tail ; whereas 
it will be remembered that the several species of Chordeiles , as a 
general rule, have six and a pygostyle. I have yet to find an 
exception to this statement. All three genera seem to possess ten 
vertebrae in the series that auchylose together in the pelvis. 
Iu Antrostomus in the dorsal series of vertebrae, as in all the 
Whip-poor-wills and Nightjars which I have examined, the haemal 
spines are comparatively long and conspicuous, the anterior ones 
being trifurcate at their extremities. 
Essentially the form of the sternum in Antrostomus agrees with 
the same bone in Plied cenoptilus, and the general form it assumes 
for the true Caprimulgine birds is very w r ell shown in the figure I 
gave of the sternum of Chordeiles texensis in plate lxi. of my 
first memoir, which can be referred to in the present connection. 
AYitli three specimens of this bone before us, one being 
chosen from each of the three genera in question, they may 
be in general distinguished by the following characters : — The 
sternum of Chordeiles is the largest of the three, and that of Pha - 
Icenoptilus the smallest. The “ costal processes ” in the Whip- 
poor-wills are simple erect spines (best marked in Antrostomus ) • 
whereas in the Nightjar they are more like laterally-compressed 
plates, and as we find them in many other birds. All three have 
the pair of deep rounded notches in the posterior end of the body 
of the bone. They are all without mauubrial processes. 
The shoulder-girdle in Antrostomus is very like those parts as 
I have already described them for Nuttall’s Poor- wdll, being only 
proportionately larger. 
Turning, now, to the pectoral and pelvic limbs iuthis American 
Whip-poor-will, we find that they also essentially agree, except 
