STTJDIES OF THE MACROCHIEES. 



369 



In the character of their heaJcs they are as widely different aa 

 any two types in the entire class Aves. 



They differ essentially in their pteryloses, and in the number 

 of the secondaries. 



Their feet are radically different, quite as different, for instance? 

 as are the feet of a Swift and a Sparrow-Hawk. 



The majority of these differences in these two types are abso- 

 lutely of an ordinal rank (for Aves). 



And now, before entering upon their internal structure, 

 let me add here the well-known fact that these birds also 

 differ essentially in their hahits, their mode of nidification, 

 and the manner of securing their food; indeed, in all these 

 particulars in their life history they are widely, very widely 

 different. 



A critical Comparison of the Pectoral Limhs of certain Cypseli 

 and Trochili. 



Prom time immemorial in Ornithology the two main charac- 

 ters upon which systematists have relied for retaining the 

 Cypseli and Trochili in the same group of birds, as related forms, 

 are the supposed similarity of the structure of their wings, and 

 the fact that both possess an unnotched f^ternum. binding that 

 these birds widely disagree in so many vital, fundamental par- 

 ticulars, it is my object to compare them very critically with 

 respect to their wing-structure, and the present section will be 

 devoted to the results of my investigations in that direction. 

 Swallows, as we know, possess a wing-structure very similar in 

 organization to the Passeres generally, so it will not be necessary 

 to make many comparisons with them in the same connection. 

 We have just seen how essentially different the wing of Trochilus 

 is from the wing of Micropus, so far as its external characters 

 are concerned : to be sure they have a superficial resemblance, as 

 both have short humeri and long pinions, but this resemblance 

 gives way when we come to compare the parts in detail. 



Eirst, then, let us examine the method of attachment of the 

 patagial muscles, surely a character which has proved itself to 

 be a useful one, and one eminently connected with the wing- 

 structure in birds, be they Swifts or Humming-birds. Now Prof. 

 Grarrod dissected a Humming-bird with the view of ascertaining 

 the point which concerns us here, and he had a specimen of 

 Patagona gigas for investigation. Moreover he made a drawing 



