342 



DR. K. 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 Chordeiles. 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 Caprimulgus, 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 CJiordeiles^ 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 Whip-poor-will and Nightjar we 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 pterylography 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 difter- 

 ences or similarities to be found in the two j^\merican genera 

 examined. The principal facts to bear in mind are that the ptery- 

 losis of the American Antrostomus vociferus differs from the 



