1887.] OF THE WINGS OF BIRDS. 357 



Plate XXXI. 

 a. The distal phalanx of digit ii. of the wing of the Barn-Owl, with the attached 

 predigitals and their coverts, showing the remicle and its relations. 



1. Ventral view. 2. Dorsal view. 



a. Predigital 1. /3. Predigital 2 (remicle). 



a'. Dorsal tectrix major to a. 



a". Ventral tectrix major to a. 



13'. Dorsal tectrix major to remicle. 



j8". Ventral tectrix major to remicle, 



1. Phalanx 2 of digit ii. 



2. Fused phalanx 3 of digit ii. 



b and c. Diagrams of the ventral and dorsal surfaces of the wing of the Wild 

 Duck, showing the points of insertion of the feathers of the different 

 groups. 

 C. Oubitals, M. Metacarpo-digitals. E. Eemicle. r. Remex. 



a. Tectrices majores. 



fi. Tectrices mediae. 



y. Tectrices minores. 



fi. Tectrices marginales. 



X. Axillars. 



h. numerals. 

 Ax. Axillary row. 

 (5). Absent fifth cubital remex. 

 Al. Alula. 



Plate XXXII. 



Figs. 1-5. Diagrams showing how the ventral tectrices majores and medife have 

 been carried over from the dorsal side, and the " ala membrana " 

 formed. 



1. The earliest condition of the feather-rudiments. 



2-4. Intermediate conditions. 



5. The condition in the adult wing. 



Eemiges — red. 



Tectrices majores (superior) — yellow. 

 Tectrices majores (inferior) — green. 

 Tectrices medioo (superior) — dark blue. 

 Tectrices media; (inferior) — light blue. 

 These diagrams represent sections across the wing in the direction x-i/ (fig. 8). 



Figs. 6-9. The remiges and upper principal coverts in the region of the wrist- 

 joint in Barn-Owl (ti), Grebe (7), Duck (8), and Lark (9). 

 1, 2, 3. 4. Metacarpal remiges (red). 

 1', 2', 3', 4'. The corresponding major covert (yellow). 

 1", 2", 3", 4". The corresponding median covert (blue). 

 * Wrist-joint. 



The plan of these feathers in section is shown above each, and represents the 

 primitive unmodified relations. 



a. Drawing of section through the large > feathers of the wing just below the 



edge of the " ala membrana " of the Pheasant. 

 (3. The same of the Duck. The proximal cubitals are not shown. 

 R. Eemex (i-ed). 

 DC. Dorsal covert, tectrix major (yellow). 

 VC. "Ventral covert, tectrix major (green). 

 S'. Eemicle. 

 * The wrist-joint. 

 Q. Fifth cubital remex present. 

 Aq. Fifth cubital remex absent. 



