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other birds habitually cleanse the bill and sides of the gape with their 

 feet, and yet have no pectination of the middle claw. 



A theory advanced by Mr. Sterland, and endorsed by Mr. Robert 

 Gray, is that since the Nightjar sits lengthwise, and not crosswise, upon 

 a bough, the serrated claw gives a secure foothold, which in so unusual 

 a position could not be obtained by grasping. But to this theory the 

 objection above made also applies, namely, that many birds, such as 

 coursers and thick-knees, have serrated middle claws, and yet are never 

 seen to perch. Some naturaHsts, and amongst others Bishop Stanley, 

 have surmised that, by means of its peculiarly-formed toes, the Nightjar 

 is enabled to carry off its eggs, if disturbed, and place them in a more 

 secure spot ; but should any such necessity arise, one would think that 

 its large and capacious mouth, as in the case of the cuckoo, would form the 

 best and safest means of conveyance. In the young Nightjar, the peculi- 

 arity in question is not at first observable ; and Macgillivray remarked 

 that in a fully fledged young bird, shot early in September, the middle 

 claw had only half the number of serrations which are usually discernible 

 in the adult. He says : " All birds whose middle claw is serrated, have 

 that claw elongated, and furnished with a very thin edge. It therefore 

 appears that the serration is produced by the splitting of the edge of 

 the claw after the bird has used it, but whether in consequence of 

 pressure caused by standing or grasping, can only be conjectured." I 

 have detected some confirmation of this in the case of the common 

 thick-knee, or stone cvcAt'N ( CEdicnemus crepitans ), in some specimens 

 of which I have remarked a very distinct serration of the middle claw, 

 in others only the barest indication of it (the edge of the claw being 

 very thin and elongated), in others again no trace of it. 



The objections, however, which have been taken to the suggested 

 use of the pectinated claw in the Nightjar, do not invalidate the state- 

 ments which have been made by Gilbert White, and other observers of 

 the bird's movements and habits ; for the homologous structures which 

 are found to exist in certain species in no way related to each other, 

 may well be designed for very different functions. I do not find in the 

 works of either Macgillivray or Yarrell, any mention made of the peculiar 



