210 ME. P. CHALMERiS MITCHELL ON SO-CALLED 



On so-called " Quintocubitalism " in the Wing of Birds; with 

 special reference to the Colwmhce, and Notes on Anatomy. 

 By P. Chalmers Mitchell, M.A., P.L.S.* 



[Eead 16th March, 1899.] 

 (Plates 12 & 13.) 



Since the results of Wray's investigations were published (1), 

 the occurrence of two well-marked modes of disposition of the 

 quill -feathers on the upper part of the wing of birds has been 

 well known, and the explanation of the existence of the two 

 conditions has been sought by many zoologists. In one mode of 

 disposition, that known as "quintocubitalism," the quill-feathers 

 which abut on the ulna are arranged in a regular and even series, 

 each feather with its upper and lower covert being of approxi- 

 mately the same size and lying at the same approximate distance 

 from its neighbours on the distal and proximal sides. In the 

 disposition termed " aquintocubital " the first four quills, counting 

 from the distal towards the proximal end of the ulna, are arranged 

 precisely as in the quintocubital wing, but, after the fourth, 

 there is a gap in which there is an u]Dper and lower covert pre- 

 cisely as in the regular arrangement but no quill between them. 

 Thereafter the quills follow in regular series. It appears as if 

 the fifth quill had been lost without any other disturbance of the 

 series, and the condition was called " aquintocubital," i. e. with- 

 out the fifth cubital, on account of this ready interpretation. 

 It appears to me that it would be more convenient to state the 

 facts in another way. Immediately distad of the cubital quills 



* [This Memoir is complementary to that by Mr. W. P. Pyeraft, which 

 follows (infra, pp. 236-2.'54). During the autumn of 1898, Mr. Pyeraft inti- 

 mated his intention of early presenting to the Society a memoir on the so-called 

 Aquintocubitalism in the Bird's wing, and in subsequent conversation with 

 Mr. Mitchell he discovered that the latter had already arrived at the same 

 main conclusion as himself, and that he had lodged a preliminary statement 

 concerning it with the Editor of a scientific journal. When these facts became 

 known to the Officers of the Linnean Society, they approached the two 

 gentlemen with a proposal that their memoirs might be presented at one of 

 the Society's meetings and published together in its Journal, and to this they 

 willingly agreed, Mr. Chalmers Mitchell very generously withdrawing the 

 afore-mentioned press notice. 



Except tbat the authors agree on the main issue, to which they came 

 " independently and unknown to one anotbei'," their papers will be found to 

 supplement each other — one author having approached the subject through 

 the study of development, the other through that of adult anatomy. — Ed.] 



