STUDIES OF THE MACROCHIEES. 



375 



stand 2, 8, 4, 5, while, as we know, in Micropus they stand 2, 3, 

 3, 3. 



As existing birds are classified, and were two such forms as 

 Micropus and Trocliilus classified upon the characters presented 

 in their pelvic limbs alone, all I can say is, that to my mind 

 there should be no hesitation whatever in placing them in widely 

 separated groups, notwithstanding the fact that the myological 

 formula of the thigh-muscles is the same. Eor even when we 

 come to examine these very muscles closely we soon discover 

 that they are quite differently formed and disposed, which should 

 also be taken into consideration in face of the fact of the mere 

 presence or absence of parts. 



For the rest, the limb in these two groups of birds to its 

 very toe-joints is about as essentially different as are the limbs 

 of an Ostrich and a Coot. 



Oil the Anatomy of the Head. 



Were I asked to pick out any two forms of existing birds from 

 any part of the world which present us with the greatest 

 number of fundamental differences so far as the anatomy of 

 the head is concerned, it would puzzle me, I think, to select 

 two more diverse types than a true Swift and a Humming-bird. 

 Indeed, from tip of beak to nape it is difficult to find comparable 

 characters that show any affinity of the forms in question at all. 

 I have already pointed out above the very evident differences that 

 are exhibited up)on a comparison of the external characters of 

 such a Swift as Micropus and any of the Trochili ; while the 

 principal differences in the skulls of these birds have been already 

 dwelt upon *. And has the day yet arrived when differences 

 of the most manifest character in the skulls of birds are to be 

 ignored in taxonomy, and set aside as of no value ? 



At the present time I have before me upwards of a hundred 

 anatomical specimens of Trochili and a great many Swifts ; but 

 for a brief resume of some of the distinctive cranial characters let 

 us choose a specimen each of CJuetura pelagica and Trochilus 

 rvfus, and see how they compare in these two types. We find 

 these characters to be as follow : — 



♦ Proc. Zool. Soc. 1885. 



