CROCKER—CROSSBILL 113 
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horny, slender, and erectile outgrowths on the forehead of Pala- 
medea comuta ; and the similar erectile, long process of Chasmo- 
rhynchus, which is partly covered with very small feathers. The 
soft crest or comb of many Phasianidze consists, like the wattles of 
other birds, entirely of the bare skin, and, being very rich in nerves 
and blood-vessels, is, as swelling organs, erectile in a different sense. 
Prominent ridges of bones, serving then for the attachment of 
powerful muscles, are likewise called “crests,’—for instance the 
crista sterni, 
CROCKER in England, according to Montagu, a name for the 
Black-headed GuLL, Larus ridibundus; but in North America (and 
perhaps also in some parts of Britain) used for the BRANT-Goose 
(Trumbull, Portr. and Names of Birds, p. 6). 
CROP, or ingluvies, the dilatation of the cesophagus before its 
entrance into the thorax. The walls of the crop seem to contain 
no other glands than the ordinary mucous glands of the cesophagus ; 
the crop is used as a receptacle for the food, which therein is 
softened and acted upon by water and the saliva and warmth of the 
bird. Between a narrow, temporarily-dilated cesophagus and a 
permanent crop-like dilatation many intermediate stages exist. A 
distinct sac-like crop is present in most seed-eating birds, as 
in the Gallinz, Columbe, Pteroclide, in Opisthocomus, Thinocorys, 
Attagis, Psittaci, and, among the Passeres, many of the Fringillide 
and the Drepanidide. The crop is less marked or only tem- 
porary in the Birds-of-Prey, the Cassowary, the Humming-birds, in 
Mormon, Pedionomus, and Panurus ; and is represented by a slight 
but permanent dilatation in the Cormorant, various Ducks and 
Storks, and in the Flamingo. It is absent in all other birds. It 
reaches its highest development in the Pigeons, consisting of a right 
and a left globular half which are united by an unpaired portion ; 
the inner walls possess numerous irregular ridges, and shew during 
the breeding-season an extraordinary activity, the cells of the 
mucous membrane proliferating and peeling off as a cheesy matter, 
with which both sexes feed their nestlings for a considerable time. 
The most peculiarly constructed crop is that of Opisthocomus ; 
the cesophagus is much widened and forms a long doubled loop, 
which rests upon the great pectoral muscles, and almost suppresses 
the anterior part of the keel of the breastbone. The walls are 
extremely muscular, and are inside furnished with numerous 
furrows and ridges, to enable the Hoacrzin to squeeze out the juicy 
leaves of the tree, Arum arborescens, upon which it feeds. 
CROSSBILL (Fr. Bec-croisé, Germ. Kreuzschnabel), the name 
given to a genus of birds, belonging to the Family Fringillide 
(FINCH), from the unique peculiarity they possess among the 
whole Class of having the horny sheaths of the Dill crossing one 
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