"aquintocubitalism:" in the bird's wing. 237 



number. The number of tbe secondaries varies greatly from 

 9 to 37. Thougb tbe primaries are packed closely together at 

 tbeir bases, tbe secondaries are more or less widely spaced 

 (Pi. 14. fig. 5). Tbe exigencies of fligbt demand tbis. 



Tbe teetrices are separable into several distinct series, forming 

 the major, median, minor, and marginal coverts, to wbicb may 

 be added the ala spuria, tbe hypopteron, and parapteron. With 

 these last we have nothing to do now. The teetrices clothe the 

 dorsal and ventral surfaces of tbe wing. The major coverts are 

 the most post-axial, and are seated in pairs on the bases of the 

 remiges — two to each remex, one dorsal and one ventral — to 

 which they are firmly attached. The median form the row next 

 in front of the major coverts, both on tbe dorsal and ventral 

 surface. There is never more than one row on the dorsal or 

 ventral surface. The minor lie beyond the median coverts, and 

 A'ary from 1 to 4-5 rows on both aspects of the wing. Beyond 

 these are tbe marginal coverts ; they occupy tbe pre-axial border of 

 tbe wing, and help to clothe both the dorsal and ventral surfaces. 



A reference to PI. 14. fig. 5 will make tbis much more clear 

 than mere description. Questions concerning the overlap, 

 variations in tbe number of rows of minor and marginal coverts, 

 their length, the absence of more or fewer of these rows on the 

 arm or manus in different groups, need not be discussed here. 

 One point, however, is noteworthy. Sundevall (7), and later, 

 and more correctly, Wray (8) pointed out that tbe major 

 and median coverts of the ventral aspect of the wing turn their 

 ventral surfaces downwards as do tbe remiges, and not upwards 

 as do all tbe other coverts of the under surface. Wray's inter- 

 pretation of this was, that these feathers bad been slowly carried 

 round from the dorsal surface of tbe wing, whilst tbe teetrices 

 of the under surface were separately derived from tbe ventral 

 surface uf the body. 



Eutaxic and Diasiatnxic Wings. 

 Tbe Bird's wing may assume one of two forms, known hitherto 

 as (1) the Quintocubital, and (2) tbe Aouintocubital (p. 2y8). 

 The two may readily be distinguished. In tbe former, each 

 pair of secondary major coverts embraces a remex between 

 thera ; in the latter, tbe remex from between tbe 5tb pair of 

 coverts is apparently missing— hence tbe name " aquintocubital." 

 Tbe perfectly regular arrangement of tbe coverts in such awing, 

 and tbe presence of a more or less distinct gap between tbe 4tb 



