48 PASSERES. CAPRIMULGIDiE. 



session of Mr. Hill, to whom I am indebted for the 

 following interesting observations. 



" White's conjecture of the purpose to which the 

 serrated toe of the Nightjar is applied, namely, the 

 better holding of the prey which it takes with its 

 foot while flying, would have been more than ren- 

 dered highly probable by an inspection of the foot of 

 the Nyctibius. The inner front toe and the back 

 toe are spread out by the great extension of the en- 

 veloping flesh of the phalanges, to such a breadth as 

 to give the foot the character and form of a hand ; 

 while the movement of these prehensile organs is so 

 adjusted that the back toe and the three front toes, 

 pressed flat against one another, can enclose any- 

 thing as effectually as the palms of the hands. The 

 [claw of the] middle toe, which is serrated in the 

 Caprimulgus, is simply dilated in the Nyctibius, a 

 peculiarity also of the swallows. Whatever defi- 

 ciency of prehension this may give it, when com- 

 pared to the power of the serrated nail of the Capri- 

 mulgus, is amply compensated for in the Nyctibius, 

 by the palm-like character of the foot, by the ex- 

 traordinary expansion of the toes, and by the quan- 

 tity of membrane connecting them together. All 

 this would be a mere waste of power if it did not 

 perform some function like that which White as- 

 signed to the foot of the Nightjar. 



" The feathers of the head, but especially those 

 around the dilated gape, are of a peculiar structure. 

 The covering of this part appears at first sight a 

 mixture of hair and feathers, but upon close inspec- 

 tion, it is found to be composed of a loosely woven 



