642 NIGHTJAR 
the east and Fernando Po on the west, and is reported to have 
occurred in Madagascar and Socotra. In this the remigial streamers 
do not lose their barbs, and as a few of the next quills are also to 
some extent elongated, the bird, when flying, is said to look as 
though it had four wings. Specimens of both are rare in collections, 
and no traveller seems to have had the opportunity of studying the 
habits of either so as to suggest a reason for this marvellous sexual 
development, though the late Mr. Joseph Gedge, who accompanied 
Sir Samuel Baker’s expedition to the Soudan, on one occasion 
observed a Macrodipteryx squatting on the ground with its long 
remiges erected perpendicularly, and the accompanying figure is from 
a sketch sent by him to his friend Mr. Marlborough Pryor. 
The second group of Caprimulgine, those which are but poorly 
or not at all furnished with rictal bristles, contains about five genera, 
of which there is here only room to particularize Lyncornis of the 
Old World and Chordiles of the New. The species of the former 
are remarkable for the tuft of feathers which springs from each side 
of the head, above and behind the ears, so as to give the bird an 
appearance like some of the “ Horned” Owxis—those of the genus 
Scops, for example; and remarkable as it is to find certain forms of 
two Families, so distinct as are the Strigid# and the Caprimulgidex, 
resembling each other in this singular external feature, it is yet 
more remarkable to note that in some groups of the latter, as in 
some of the former, a very curious kind of DimorpHisM takes place. 
In either case this has been frequently asserted to be sexual, but on 
that point doubt may be fairly entertained. Certain it is that in some 
groups of Nightjars, as in some groups of Owls, individuals of the 
same species are found in plumage of two entirely different hues— 
rufous and grey. ‘The only explanation as yet offered of this fact is 
that the difference is sexual, but, as just hinted, evidence to that effect 
is conflicting. It must not, however, be supposed that this common 
feature, any more than that of the existence of tufted forms in each 
group, indicates any close relationship between them. The resem- 
blances may be due to the same causes, concerning which future 
observers may possibly enlighten us, but at present we must regard 
them as analogies, not homologies. The species of Lyncornis inhabit 
the Malay countries, one, however, occurring in Burma and India. 
Of Chordiles the best-known species is the Night-hawk of North 
America, C. virginianus or popetue, which has a wide range from 
Canada to Brazil. Others are found in the Antilles and in South 
America. 
We have next to consider the birds forming the genus Podargus 
and those allied to it, whether they be regarded as a distinct Family, 
er as a subfamily of Caprimulgide. As above stated, they have 
feet constructed as those of Birds normally are, and their sternum 
seems to present the constant though comparatively trivial difference 
