STUDIES OE THE MACROCHIRES. 
339 
As the external characters of these commoner American forms 
are well known, and are fully set forth in general works upon 
ornithology, I need not introduce them here. 
Suffice it to say that these characters fully rank as ordinal 
ones in so far as they distinguish these birds from either the 
Swifts or the Humming-birds. 
When I say ordinal ones I mean as pertaining to an order in 
the sense which that division holds as applied to Avian taxonony, 
and not to other vertebrate classes, where, as we know, structural 
differences are far greater than are to be found even among 
the extremes in the class Aves. 
Having gone carefully over all the literature and material now 
available that bears in any way upon the present group, I find 
no reason to change my opinion as originally set forth in my 
memoir published in the Proc. Zool. Soc. 1885, where I proposed 
(p. 914) that all the Caprimulgine birds should be considered 
as constituting an order — the order Caprimudgi. I men- 
tioned a number of the more doubtful forms that should be 
admitted to this order, as Nyctibius , Steatornis, Podary us, and 
others. Scarcely a doubt exists now, I think, in regard to the 
relation these birds bear to the Owls, through Steatornis, and, 
further, they have no particular affinity either with the Humming- 
birds nor the Swifts. 
Their morphology is full of interest, and will repay very careful 
research in the future. 
In the present connection it is my intention to lead off with a 
full description, if the one fine specimen in my possession will 
admit of it, of the anatomy of our common American Whip- 
poor-will ( Antrostomus vociferus ), making it comparative w r ith 
the more aberrant genus Cliordeiles, and then add something 
further in regard to the skeleton of Phalcenoptilus Nuttalli. 
On the Pterylograpliical tracts of Antrostomus and Cliordeiles 
( omitting the remiges and rectrices). 
Having carefully plucked my specimen of Antrostomus voci- 
ferus and one of Cliordeiles texensis, and opened before me my 
copy of Sclater’s edition of Nitzsch’s ‘ Pterylography ’ at the 
proper page and plate (p. 87, pi. iv. figs. 1 & 2), I am prepared 
to present a few remarks upon the pterylosis of the Caprimulgine 
birds in my hands. 
