72 University of California Publications in Zoology. [Vol. 7 



swift from the little Vaux swift, with which it was here asso- 

 ciated; but the two species differ in many minor respects also. 

 The black swift soars a great deal and flutters its wings com- 

 paratively little, is almost absolutely silent, and individuals 

 were seldom seen pursuing one another. 



It was undoubtedly breeding somewhere in the vicinity for 

 one of the females secured contained an egg that would have 

 been laid in a few days. 



It was met with again at Portage Cove, Revillagigedo Island, 

 where a few individuals appeared nearly every evening at dusk, 

 flying about until dark. It is rather curious that the species was 

 not observed on the Chickamin River, on the mainland directly 

 opposite Portage Cove, the character of the country being very 

 similar to that at Boca de Quadra. At Bradfield Canal Hassel- 

 borg saw a large black swift that he supposed was of this species. 



Eight specimens were secured, two males and four females 

 at Boca de Quadra (nos. 9360-9365), and two males at Portage 

 Cove (nos. 9366, 9367). The four males are uniform sooty black 

 (save for the paler markings about the head), only one (no. 9366) 

 showing slight whitish tips on the feathers of the abdomen and 

 the lower tail coverts. Of the four females, one is like the males 

 in that it is uniformly black (except for a single pure white 

 feather on the upper breast). The other three have the feathers 

 of the abdomen and the lower tail coverts tipped with white in 

 varying degrees. These white tips probably disappear as the 

 individual becomes older, and when fully adult the sexes are 

 apparently alike in coloration, but from the specimens in hand 

 there seems to be one point in which they constantly differ. The 

 four males have the tail deeply forked; in the four females it 

 is uniformly square, there being no difference in this respect 

 between the black individual and the white marked ones. In 

 the males the tail is so deeply forked that the lower coverts extend 

 beyond the middle rectrices. 



I believe that this is the first time that the species has been 

 taken in Alaska. 



The eight specimens secured measure as follows : 



