Skull.—The skulls in all three subfamilies have essentially the same general appearance and structure, the most marked differences being, as would be expected, in the bills and associated bones.

The most specialized bill is to be found in Dulus; its bill is decurved, and the associated bones are correspondingly changed for support of the bill. For example, the palatines and "vomer" are much wider, the palatines are more concave from below and have longer posterior processes than the corresponding bones in Bombycilla. Moreover, the "vomer" in Dulus and in Phainoptila is larger and heavier than in Bombycilla, and the quadrate and pterygoid bones are relatively large for support of the beak. The palatines, however, are weak in Phainoptila. In the Ptilogonatinae, with the exception of Phainoptila, the wings of the palatines flare more than in Bombycilla, but not to the extent that they do in Dulus, nor does the palatine bone present a concave appearance in the Ptilogonatinae. The premaxilla is a relatively weak bone in Bombycilla and Phainopepla, stronger in Ptilogonys, and is notably heavy in Phainoptila and Dulus, and in these latter two genera shows a sharply-ridged tomium. The maxillae connect to somewhat widened nasal and naso-lateral processes in all the genera, and the premaxillae narrow abruptly from this point forward. In the family, Phainopepla and Phainoptila show the least flaring in this region.

1.Phainoptila m. melanoxantha, sex?, MNH no. 26493, 15 mi. SE Cartago, Costa Rica.
2.Ptilogonys caudatus, male, MNH no. 24492, 15 mi. SE Cartago, Costa Rica.
3.Phainopepla nitens, male, MNH no. 24752, Pima Co., Arizona.
4.Ptilogonys cinereus, female, Louisiana State University no. 297,
Xilitla Region, San Luís Potosi, Mexico.
5.Dulus dominicus, female, USNM no. 292652, Don Don, Haiti.
6.Bombycilla cedrorum, male, MNH no. 15331, Bexar Co., Texas.
7.Bombycilla garrula, sex?, USNM no. 223895, Bozeman, Montana.

8.Phainoptila m. melanoxantha, sex?, MNH no. 26492, 15 mi. SE Cartago,
Costa Rica.
9.Ptilogonys caudatus, male, MNH no. 24492, 15 mi. SE Cartago, Costa Rica.
10.Phainopepla nitens, male, MNH no. 24754, Pima Co., Arizona.
11.Ptilogonys cinereus, female, Louisiana State University no 297, Xilitla
Region, San [Luís] Potosi, Mexico.
12.Dulus dominicus, female, USNM no. 292652, Don Don, Haiti.
13.Bombycilla cedrorum, male, MNH no. 15331, Bexar Co., Texas.
14.Bombycilla garrula, sex?, USNM no. 223895, Bozeman, Montana.

15.Phainoptila m. melanoxantha, sex?, MNH no. 26493, 15 mi. SE Cartago, Costa Rica.
16.Ptilogonys caudatus, male, MNH no. 24492, 15 mi. SE Cartago, Costa Rica.
17.Phainopepla nitens, male, MNH no. 24752, Pima Co., Arizona.
18.Ptilogonys cinereus, female, Louisiana State University no. 297, Xilitla Region, San Luís Potosi, Mexico.
19.Dulus dominions, female, USNM no. 292642, Don Don, Haiti.
20.Bombycilla cedrorum, male, MNH no. 15331, Bexar Co., Texas.
21.Bombycilla garrula, sex?, USNM no. 223895, Bozeman, Montana.