436 



NATURAL HISTORY OF BIRDS. 



present super-family from the Caprimulgidae. Osteologically the swifts and humming- 

 birds resemble each other closely in all respects except in the shape of the bones of 



the face. The breastbone 

 is highly characteristic, 

 having a high keel, and 

 an entire, unnotched pos- 

 terior margin. The pro- 

 portions of the different 

 sections of the wings are 

 also noteworthy, the hu- 

 merus being very short, 

 the forearm longer, and 

 the hand extremely long, 

 whence Nitzsch's name 

 of the group. The myo- 

 logical formula is A-J-, 

 unique amongst Picarian 

 and Passerine birds, and 

 only shared by the owls. 

 The tensor patagii brevis 

 is quite peculiar, no ten- 

 don being developed, and 

 the fleshy belly running 

 on to a special tendon 

 which springs from the 



lower end of the outer surface of the humerns, and is 

 continued, parallel to the forearm, along the radial 

 margin to the hand (Fig. 219). As to the visceral an- 

 atomy we only mention the absence of caeca, concom- 

 itant with the absence of tuft to the oil-gland, a 

 feature which leads us to the pterylography, in regard 

 to which we point to the uniquely small number of 

 secondaries, six to seven. 



From all this it is evident that the swifts and hum- 

 ming-birds are very closely allied, notwithstanding the 

 extreme specialization of the facial part of the head 

 in two opposite directions. The swifts have the 

 mouth split to beneath the eyes, and the bill is ex- 

 tremely short, broad at base, and the gape extraordi- 

 narily wide ; the palate is built on the principle of 

 complete asgithognathism, "the vomerine bones being 

 grafted upon the nasal wall." In the humming-birds, 

 on the other hand, the bill is long and narrow, the 

 mouth not split, consequently the gape also narrow, 

 and the palate is, according to Parker, schizognathous, 

 the vomer being pointed anteriorly, and only tied to the alinasal wall by a fibrous liga- 

 ment, but not grafted upon it. But even in the palatal structure the relationship 

 between swifts and humming-birds is manifested by the development of the maxillo- 



Fio. 218. Apaloderma narina, African 

 trogon. 



