CROCKER—CROSSBILL 1 1 3 



horny, slender, and erectile outgrowths on the forehead of Pala- 

 medea coniuta ; and the similar erectile, long process of Chasmo- 

 rhynchus, which is partly covered with very small feathers. The 

 soft crest or comb of many Phasianidse 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. 



CROCKEE, 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-Goosb 

 (Trumbull, Portr. and Names of Birds, p. 6). 



CROP, or ingluvies, the dilatation of the oesophagus before its 

 entrance into the thorax. The walls of the crop seem to contain 

 no other glands than the ordinary mucous glands of the oesophagus ; 

 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 oesophagus 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 Gallinse, Columbse, Pteroclidse, in Opisthocomus, Thinocorys, 

 Attagis, Psittaci, and, among the Passeres, many of the Fringillidge 

 and the Drepanididas. 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 oesophagus is much widened and forms a long doubled loop, 

 which rests upon the great pectoi'al 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 HoACTZiN to squeeze out the juicy 

 leaves of the tree, Arum arborescens, upon which it feeds. 



CROSSBILL (Fr. Bec-croisS, Germ. Kreuzschnabel), the name 

 given to a genus of birds, belonging to the Family Fringillidx 

 (Finch), from the unique peculiarity they possess among the 

 whole Class of having the horny sheaths of the bill crossing one 



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