STUDIES OF THE MACROCHIRES. - 
349 
its skeleton; and for farther 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. Nutt alii) in order to show how 
well it agrees with Caprimulgus and Antrostomus, and differs from 
the skull in Chordeiles 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, Phalcenoptilus 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- 
tail’s Nightjar were in 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- 
irostomus , I find my account of the corresponding 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 vertebrae 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* 
