342 DR. R. w. shufeldt’s morphological 
As shown in PI. XVIII. fig. 10, the “femoral tracts ” are very 
definitely marked in Antrostomus ; they are broader and more 
diffuse in CliorcJeiles. The feathering of the integuments of the 
pelvic limbs of either of these genera is somewhat sparse and 
scattered, and without definite pattern. 
Turning now to the ventral aspect of the body, we find, in 
common with what Nitzsch found in Gaprimulgus, that in these 
American forms the anconal surface of the wings are very thickly 
feathered all over ; the feathering becomes scattered as we pass 
on to the patagium ; but the free anterior edge of this latter 
membrane has a narrow and dense row of small feathers inserted 
along its entire length. 
I have already described above the pterylosis of the anterior 
cervical region ; this leaves us to consider the feathering of the 
pectoral aspect of the body. Here we find that both Antrostomus 
and Chordeiles agree very closely with the European Night- 
jar, as the pterylosis of that bird has been described by Nitzsch. 
The ventral tracts in all are broad, broader than the well- 
defined humeral tracts of the dorsal aspect, being rather widely 
separated in front, and blending somewhat with the aforesaid 
humeral tracts at the summit of either shoulder. 
The median apterium of the chest (if we may apply this term to 
it here) is uniformly, though thinly, feathered in both Antrosto- 
mus and Chordeiles , which sparse feathering is extended over the 
abdomen below. This condition is not taken into consideration 
by Nitzsch in his figure of these parts in Caprimulgus . From the 
posterior extremity of the broad ventral tract on either side in 
the "VVhip-poor-will and Nightjar w r e find a narrow contour 
abdominal tract running backwards on a curved line to join the 
fellow tract of the opposite side behind the vent. 
The pelvic limbs are fairly well covered with feathers upon 
this aspect, though not so much so as they are upon the reverse 
sides. 
So much, then, for the pterylograpby of the Caprimulgine 
birds now under consideration. After the detailed way in 
which I have attempted to describe it in the above paragraphs, 
it will be hardly necessary to present synoptical tables of differ- 
ences or similarities to be found in the two American genera 
examined. The principal facts to bear in mind are that the ptery- 
losis of the American Antrostomus vociferus differs from the 
