STUDIES OE THE MACROCHIRES. 
379 
being satisfied with that (taken in connection with a few other 
salient characters), very often the rest of the bird’s economy 
has not been examined nor even taken into consideration at all. 
Why the pelvis has not proved an equally valuable character 
in the list of classificatory characters, is simply because the 
systematist cannot so readily say pelvis 2-notched, pelvis un- 
notched, and so on. Yet the pelves of birds, when carefully 
compared, offer fully as good distinctive characters for taxo- 
nomic purposes as the sternum. I have already pointed out the 
fact that the pelvis of a Trochilus is as different from the pelvis 
of a Cypselus as any two birds’ pelves can well be. Further, their 
sterna, when we really take all their characters into considera- 
tion, apart from the fact that both happen to be unnotched, are 
very differently fashioned bones. Both are unnotched, to be 
sure, — but so are the sterna of some Petrels ! Were the fact that 
the sterna of both Cypseli and Trochili are nunotched of any signi- 
ficance, so far as affinity is concerned, then surely the remainder of 
the organization in these birds would be more or less in harmony, 
and not at the widest variance, as is the case ! What I mean by tins 
is easily shown in the shoulder-girdles of the two types in question : 
thus, the coracoid of a Trochilus is a very uniquely-formed bone 
(P. Z. S. 1885, pi. lx. fig. 5), and very different from the great 
majority of birds. In the Swifts the coracoid is like that of the 
Swallows. Again, the scapula in Trochilus is unlike the corre- 
sponding bone in a Swift : consequently, this being the case, I 
attach little or no importance, so far as affinity is concerned, 
to the fact that their furcuhe happen to possess some marked 
resemblance. For we well know that this latter component of 
the girdle is that which becomes modified in accordance with 
the flight of its owner, while the coracoid can be far better 
relied upon for any affinity it may show as a character amongst 
forms more or less related. Swifts are birds of long-sustained 
flight, Humming-birds are great fliers, and so are Albatrosses ; and 
were we to increase in size the os furcula of a Swift and a Hum- 
ming-bird to the size of the bone in an Albatross, we should be 
surprised to find how much they resemble each other. 
Seeing now how very different the thoracic and pelvic, or 
really the trunk-skeletons of Swifts and Humming-birds actually 
are, let us next examine into some of the organs and viscera 
which they enclose. 
LINK. JOURN. — ZOOLOGY, VOL. XX. 
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