STUDIES OF THE MACROCHIEES. 
369 
In the character of their beaks they are as widely different as 
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 habits, 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 Limbs of certain Cypseli 
and Trochili. 
From 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 sternum. Finding 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. 
First, 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. 
Gfarrod 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 
