_M.
pseudotemporalis profundus_, the muscle that functions simultaneously
as an adductor of the lower jaw and retractor of the upper jaw, in the
White-winged Dove was the character found in the jaw musculature that
could be used to support the contention that _Zenaidura_ and _Zenaida_
represent distinct genera. Larger size of this muscle in the white-wing
seems to be related to its elongated beak. The long beak apparently is
used for nectar-feeding in flowers of the Saguaro Cactus.

Excluding the beak, skulls of the white-wing and Mourning doves are of
nearly the same shape. Previous investigators have shown that in
_Zenaida_ and _Zenaidura_ plumage patterns are similar, nesting habits
and eggs are nearly identical, blood proteins are similar, and one
"intergeneric" hybridization in nature is known.

Consequently, it is concluded that species of the two alleged genera
are congeneric, and I agree with Goodwin (1958) that the genus
_Zenaida_ (Bonaparte, 1838:41) should include the Mourning Dove, Eared
Dove, Socorro Dove, Zenaida Dove, and White-winged Dove. Their Latin
binomina are _Zenaida macroura_, _Zenaida auriculata_, _Zenaida
graysoni_, _Zenaida aurita_, and _Zenaida asiatica_, respectively.

[Illustration: FIG. 1. Medial view of left ramus of lower
mandible of Mourning Dove. x 2-1/2.

FIG. 2. Lateral view of right ramus of lower mandible of
Mourning Dove. x 2-1/2.]

[Illustration: FIG. 3. Dorsal view of lower mandible of
Mourning Dove. x 2-1/2.

FIG. 4. Ventral view of lower mandible of Mourning Dove.
x 2-1/2.]

[Illustration: FIG. 5. Dorsal view of right quadrate of
Mourning Dove. x 5.

FIG. 6. Dorsal view of right pterygoid of Mourning Dove. x 5.

FIG. 7. Ventral view of right quadrate of Mourning Dove. x 5.

FIG. 8. Ventral view of right pterygoid of Mourning Dove. x 5.]

[Illustration: FIG. 9. Right lateral view of skull of Mourning
Dove. x 2-1/2.

FIG. 10. Ventral view of skull of Mourning Dove. x 2-1/2.]

[Illustration: FIG. 11. Cross section of skull of Mourning Dove;
anterior view. x 2-1/2.

FIG. 12. Dorsal view of right quadrate of Mourning Dove showing
movement which protracts the upper mandible (broken line). x 5.]

[Illustration: FIG. 13. Right lateral view of the jaw musculature of
the White-winged Dove; superficial layer, x 5.

FIG. 14. Right lateral view of the jaw musculature of the Mourning
Dove; superficial layer. x 5.]

[Illustration: FIG. 15. Dorsal view of the jaw muscula