106 Mr Macgillivray's Remarks on the Middle Claw, 



Carbo, Pelecanus, Sula, and Phaeton, the margin of the middle 

 claw is thin and distinctly serrated. In the grebes, in which 

 the claws are quite flat and round, the extremity of that of the 

 middle toe is also serrated, or rather cut into by parallel lines. 

 Lastly, In the genus Caprimulgus, in which the inner margin of 

 the middle claw is extremely thin, so as to be quite flexible, 

 that margin is regularly, beautifully, and deeply serrated, inso- 

 much that it may be said to be pectinated ; while in the inti- 

 mately allied genus Podargus, the claws of which are of a diffe- 

 rent form, the margin is entire. 



The serrature of these claws is not like that of the 'leaves of 

 plants, or the teeth of a saw, but consists of short parallel cuts 

 in the edge of the claw, not at right angles to the central line, 

 but more or less oblique, and directed towards the base, some- 

 what like the barbs of a quill, parallel, and in contact at the 

 edges. They are in general, but not always, equally distanced ; 

 and the thinner the claw is, the more regular they usually are. 

 The serratures towards the end of the claw are more or less 

 broken. Sometimes there is, in consequence, a large piece of 

 the inner edge wanting, and sometimes, especially in very thin 

 claws, as in those of the goatsuckers, the end of the claw is 

 broken off. Such are the facts known to me on this subject. 



When certain persons have observed a fact in structure, they 

 are desirous of knowing its relation to function, and employ 

 various methods for this purpose ; but, on the whole, conjecture 

 is the mode usually adopted, for observation is not suited to the 

 genius of all who call themselves naturalists, and fancy is a ready 

 solvent for all gordian knots in physiology. In the Journal of 

 the Royal Institution of Great Britain, for October 1830, there 

 is a paper on the Cleanliness of Animals, by Mr Rennie, in 

 which he takes occasion to allude to the pectinated structure of 

 the claw of the middle toe of the fern-owl or goatsucker. The 

 following are his remarks in a condensed form. 



The bird alluded to has the middle claw cut into serratures, 

 like a saw or a short-toothed comb. White of Selborne seems 

 to think this structure given for the purpose of enabling it to 

 seize insects. Mr Dillon''s observations lead him to suppose 

 that the serratures are employed by the bird to comb its whisk- 

 ers, Mr Swainson thinks that the fact of an American group 



