Vol. XXIII 



ijJoip 11 ] Clark, Pterylosis of Swifts and Hummingbirds. 



73 



Hum, which is correspondingly narrow. The tarsus is feathered 

 part way down in front. The skin on the hand is not specially 

 dark. There are 10 rectrices, 10 primaries and 9 secondaries 

 and the wing is quincubital. The alula consists of 2 feathers. 



Specimen examined. 



Thompson (: 01) has given a very detailed account of the ptery- 

 losis of the head and wing of Collocalia and a somewhat briefer 

 description of that of the body. He has also figured the dorsal 

 aspect of the plucked bird. So far as the head and wing are con- 

 cerned, his figure and descriptions are very good, but it is neces- 

 sary to take exception to his statements concerning the cervical 

 and femoral tracts. He says that the dorsal tract " runs more than 

 half way up the neck" but does not mention any connection with 

 the pterylse on the head, and his figure does not show any; either 

 his specimen was peculiar and I must believe, abnormal, or else 

 he has overlooked the real connection which exists. He also states 

 that the "pectoral tracts are. . . .separated from the feathering of 

 the neck"; if that is correct, I must consider the specimen still 

 more unique. The statement that there is "no well-defined fem- 

 oral tract" is not so contradictory to his own figure and to what 

 I have described above, as at first appears, for on page 324, he 

 refers to a "lumbar" tract in Collocalia, which indicates that he 

 there uses that term for what is, in this paper, called "femoral"; 

 the word "lumbar" is not used elsewhere in his paper. It is greatly 

 to be regretted that these discrepancies should occur between 

 his paper and my observations. Further study of the pterylosis 

 of this genus is very desirable. 



