STUDIES OF THE MACEOCniRES. 



349 



its skeleton ; and for further description these will answer all the 

 purposes required. In the present paper, however, I have thought 

 it best, for the sake of completeness, to add three figures of the 

 skull of Nuttall's Poor-will (P. Nuttalli) in order to show how 

 well it agrees with Capriinulgus and Antrostomus, and diff"ers from 

 the skull in Chordeile^ given in my former memoir (PI. LIX. 

 figs. 1, 2, and 4). 



Upon more careful and extended examination, I find that, 

 except in point of size, PhalcBmptilus being about one third less 

 than Antrostomus, the skulls, mandibles, and hyoidean appa- 

 ratuses of these two forms are very much alike indeed, in all 

 essential particulars. And as the characters of the skull of the 

 Whip-poor-will are well known, and, further, as I present here- 

 with figures in the Plate of the skull of the Poor-will, I believe 

 that any further comments upon this part of the subject would be 

 superfluous. 



One point, however, in respect to the hyoid. In my former 

 paper I made the statement that in it the basibranchials in Nut- 

 tali's Nightjar were ia two pieces. This was true for the speci- 

 men examined, although in the skeleton of Antrostomus before 

 me these parts are anchylosed together, which may be the case in 

 all old birds of both these genera. Chordeiles has them in one 

 piece; and I am led to believe from this that it will be found 

 to be generally the case in our N. -American Nightjars. 



Passing next to the remainder of the axial skeleton in An- 

 trostomus^ I find my account of the corresjDonding parts for 

 Chordeiles and Phalcenoptilus Nuttalli (P. Z. S. 1885, p. 903) to 

 be so complete that it leaves but little here to be added. 



Upon carefully re-comparing the axial skeletons of the three 

 genera Chordeiles, Phalcenoptilus, and Antrostomus, now in my 

 hands, it confirms my previous notions as to their agreements 

 and disagreements ; and, as one would naturally expect, the 

 skeletons in the two Whip-poor-wills, or rather the Whip-poor- 

 will and Nuttall's Poor-will, are most alike. 



The skeleton in a specimen of a Nightjar has already been 

 described in the place just alluded to ; and now I find that Antro- 

 stomus agrees with Phalcenoptilus in having eleven vertebra? in 

 the cervical division of its spine before we come to that which is 

 the first in the column to have free ribs attached to it. These 

 ribs in the Poor- will, however, are described as being rather long ; 



27* 



