iS86.] Corresfotidc7ice. AQ\ 1 



Anatomists have long known that in avian forms, such as the C\"p.seH 

 and Trochili, wherein the powers ot~ tlight have through time heen hrought 

 to great perfection and capable of a high degree of velocity-, that it is nec- 

 essarily accompanied bj corresponding modifications of structure, such as 

 a deepening of the sternal keel, and changes "in the shape of the hume- 

 rus and its processes," as remarked upon bj' Dr. Stejneger. That the 

 corresponding "processes" have become more conspicuous is not to be 

 wondered at when we think for a moment and take into consideration the 

 fact that thej probably have been acted upon by the corresponding muscles 

 involved in the Jiight. In other words, when we come to sift out the char- 

 acters wherein the Cypseli and Trochili ^;-/«c/]^rt//}' agree we find them to 

 be just such ones as I have elsewhere pointed out. and in each instance 

 are found to be structural characters, the modifications of which are due to 

 similar habits of the forms in question, but this by no means satisfies my 

 mind that the groups should be, or are closely aflined. I think sometimes tax- 

 onomists too often lose sight of the lines of descent of the class Aves in 

 time, and in their eagerness to show relationship of the remnants of ex- 

 isting forms or groups in recent times, overlook.the great gaps that prob- 

 ably exist among the twigs of the branches and stems that represent the 

 tree of their pedigree. 



Notwithstanding Dr. Stejneger's warning against placing too mvich re- 

 liance upon the skeletal characters for our guidance, I must still insist 

 that tlie characters (as we find them in forms which we are comparing) of 

 the skull and axial skeleton are among the most reliable if not the most 

 reliable we have. If there be better ones in any vertebrate organization I 

 have not been so fortunate as yet to have met with them. If I find that 

 the number of t;e/'z'£?/;;-(^ constantly differed in any two birds, and their skulls 

 ai-e of a radically different type, why I would no more be swayed from my 

 opinion that they were members of a different order, as orders are re- 

 garded in ornithology, than I could be brought to the belief that anatomical 

 characters are valueless in taxonomy. Certainly finding an additional 

 pair of primaries or secondaries in the wing, in either case, would have 

 but little weight towards altering mv first opinion, based as I say, on 

 what I had found in the cranium and column. Now to take the skull 

 of a Swift and a Hummingbird as an example, all, absolutely all, of the 

 leading characters as we find them in the representatives of these two 

 groups are at variance while quite a number of these characters agree in 

 this part of the skeleton with the Swallows and Swifts, and others can 

 easily be shown in the latter birds to be demonstrable departures due, 

 probably, to unknown causes from the typical passerine ones. 



Since the appearance of my memoir in the 'P. Z. S.' a considerable 

 amount of material (Macrochires) has come to my hands, thanks to some 

 of the members of the A. O. U. and associate members, and others. A 

 superficial examination of some of this but satisfies me of the correctness 

 of my first conclusions, and if those conclusions are to be modified at all it 

 will be in regard to the Swifts, which I think can be shown to be a group of 

 birds also entitled to a separate order, as orders go in systematic ornithology, 



