350 



DE. R. W. SHTJFELDT S MORPHOLOGICAL 



whereas iu 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. 

 vertebrae. 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 CJiordeiles. 



Antrostomus also agrees with the Poor-will in having hut Jive 

 free vertebrae and a pygostyle in the skeleton of its tail ; whereas 

 it will be remembered that the several species of CJiordeiles, 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 te7i 

 vertebrae in the series that anchylose together in the pelvis. 



In 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 o^ thQ sternum in Antrostomus agrees with 

 the same bone in ^lialcBnojptilus, and the general form it assumes 

 for the true Caprimulgine birds is very well shown in the figure I 

 gave of the sternum of Ohordeiles texensis in plate Ixi. of my 

 first memoir, which can be referred to in the present connection. 

 With 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 CJiordeiles 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 deejD rounded notches in the posterior end of the body 

 of the bone. They are all without manubrial processes. 



The sJioulder -girdle in Antrostomus is very like those parts as 

 I have already described them for Nuttall's Poor-will, being only 

 proportionately larger. 



Turning, now, to the pectoral and pelvic limbs in this American 

 Whip-poor-will, we find that they also essentially agree, except 



