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 Luis 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.] This flaring, immediately lateral to the antorbital plate, is common to all Bombycillids and constitutes a major skeletal characteristic useful for recognition of the members of the family, since the swelling is easily discernible both externally and on the cleaned skulls. In _Phainopepla_ there is much variability in this character; some specimens have a narrower antorbital bridge than others. Only one skeleton of _Phainopepla n. nitens_ was available. The flaring in the skull of this specimen is identical with that in _Ptilogonys_. Among the skulls of _P. n. lepida_ in the University of Kansas Museum of Natural History, is No. 19228, a juvenile, taken 5 miles south of Tucson, Arizona. In this specimen, the flaring in the antorbital region is clearly evident and equal in amount to that in skulls of _P. n. nitens_, but the bird had not attained full skeletal growth. However, the flaring of the antorbital region appears to be common in the nestlings of many species of passerine birds. Other specimens of the subspecies _lepida_ show a varying amount of flaring, the least (in the series available) being in No. 24754, MNH, in which the proportion of the skull (length divided by width) closely corresponds to that in _Phainoptila_; the skull of No. 24754 is long and thin, and the base of the bill is only slightly swollen. The skull of _Phainopepla nitens lepida_ is more generalized than that of _Phainopepla n. nitens_, having a longer and narrower bill like the generalized _Phainoptila_. In _Phainopepla n. nitens_ and in members of the genus _Ptilogonys_, more flaring occurs in the antorbital region.