The primaries differ from all the other quill feathers in having the posterior half of the vane much wider than the anterior half. They are ten in number, and of these six, the metacarpal quills (fig. 57, 14), are attached to the second and third metacarpals, one, the ad-digital (fig. 57, 15), to the phalanx of the third digit, two, the mid-digitals (fig. 57, 16), to the first phalanx of the second digit, and two, the pre-digitals (fig. 51, 17), to the second phalanx of the second digit. One of the pre-digitals is very small, and is called the remicle (fig. 57, 11).
Fig. 56. The wing of a Wild Duck (Anas boschas).
The upper figure shows the dorsal side of a right wing, the lower figure
the ventral side of a left wing. × 1/3. (Brit. Mus.)
| 1. scapulars. | 6. metacarpo-digitals or |
| 2. tectrices marginales. | primaries. |
| 3. tectrices minores. | 7. tectrices mediae. |
| 4. bastard wing. | 8. cubitals or secondaries. |
| 5. tectrices majores. | 9. pennae humerales. |
| 10. pennae axillares. |
In addition, a group of three quill feathers is attached to the first digit, constituting the bastard wing or ala spuria (fig. 56, 4).
The secondaries or cubitals (fig. 56, 8) form a group of seventeen feathers, attached to the ulna; they are shorter than the primaries, and do not have the posterior half of the vane much wider than the anterior half.
The humerals (figs. 56, 9 and 57, 12) form a group of eight small feathers, of varying length, attached to the anterior half of the humerus.
