84 



Clark, Pterylosis of Swifts and Hummirujbirds. 



["Auk 

 LJan. 



Specimen examined. 



Selasphorus. 



In this genus, the femoral tracts are extended further backwards 

 and downwards than in most hummingbirds, so that there is a 

 slight connection between them and the group of under tail coverts. 

 The legs are feathered to the tarsal joint. There are 6 secondaries, 

 and the wing is probably normally aquincubital. Of the 10 rec- 

 trices, the first is longest and fifth shortest in the male, while in 

 the female of platycercus the formula is 2-3-1-4-5. 



Spec ime n s examined . 



Mellisuga. 

 (Plate III, Fig. 4.; 



Although no adults were examined, there is no indication in 

 the nestlings that the pterylosis differs from that of Trochilus. 

 Even in the embryos, the characteristic features of the pterylosis 

 are evident. In the nestlings, the feathering of the head shows 

 some peculiarities, which are illustrated in the figure given. 



