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. [Illustration: Figs. 1-7. Skulls in lateral view of five genera of Bombycillidae. Natural size. 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 Luis 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.] [Illustration: Figs. 8-14. Skulls in ventral view of five genera of Bombycillidae. Natural size. 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 Luis 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.] [Illustration: Figs. 15-21. Skulls in dorsal view of five genera of Bombycillidae. Natural size. 15. _Phainoptila m. melanoxantha_, sex?, MNH no. 26493, 15 mi. SE Cartago, Costa Rica.