BIRDS — CORVIDAK — CORVUS. 559 



CORVrS, Liiiiiaous. 



Corrus, I.is'N'AEiis, S>st. Nat. 1735. Typo Corvus corax, L. 



Cii Tlio nasal fuatlicrs li-iictlioiir<l, rcacliiii),' to or liojuml the middle of llie liill. Nostrils larje, circuliir, ovcrliunc behind 



by iiioiubraiie, tbo edges rounded ulnowliero. Rictus without bristles. liill nearly us long us lliu tursus, very stout ; much higher 

 than broad at ilia base ; culnion much arched. Wings reaching to or nearly to the tip of the tail. Tarsi longer than the middle 

 toe, with a series of small scales on the middle of each side scparatmg the anterior scutcllato portion from the posterior con- 

 tinuous plates. Side of the head occasionally witii nearly naked patches. Tail graduutcd or rounded ; the outer four primaries 

 siouated internally. 



The true crows are readily distinguished from the other Corvidae by the characters assigned 

 ahove, the GarruVine forms, with long wings, being distinguishable by other characters. The 

 leathers at the base of the bill completely conceal the nostrils, and extend over the basal half 

 of the bill, or even more. The lateral toes are equal, and reach nearly to the base of the middle 

 claw ; the hind toe a little further. The hind claw is a little shorter than its digit, but larger 

 than the middle anterior claw. The lower parts of the postero-lateral plates of the tarsus 

 exhibits a few transverse scutellate divisions. 



The determination of the species of crows is a matter of much uncertainty, owing to the 

 uniformity of their plumage, and the fact that it is difficult to find them with the feathers 

 alW'ully developed at the same time. Nearly one half of all the specimens in the collection 

 before me have some of the quills only partly grown out. There also appears to be much vari- 

 ation in size with age and with locality, as well as in proportions, and I am inclined to 

 think that, contrary to what has been observed to be the case in other families, the Corvidae of 

 the same species in southern localities are larger than those from points further north. Should 

 this be substantiated it may tend materially to reduce the number of North American species. 

 Thus the Corvus cacalotl may be only a large southern carnivorus, the caurinus a uorthern, and 

 Y&T . Jloridanus a southern americanus. Four species are certainly permanently distinct : C. 

 carnivorus, C. cryptoleucus. C. americanus, and C. ossifragus, whatever be the fate of the others. 



The following diagnosis may serve to distinguish the American crows from each other. 



A. Ravens. — Feathers of the chin and throat stiffened, elongated, narrow, lanceolate, and 

 with their outlines very distinct. 



Length about 24.50 inches ; wing about 17 ; tail, 10. Outer tail feathers about 1.60 

 to 1.90 inches shorter than the central one C. carnivorus. 



Length about 24 inches ; wing near 18 ; tail, 10.50. Outer tail feather about 2.30 inches 

 shorter than the central C. cacalotl. 



Length about 21 inches; wing, 14; tail, 8.50. Outer tail feather about 1.25 inches 

 shorter than the middle one. Feathers of the neck and breast pure snowy white at 

 the base C. cryptoleucus. 



B. Crows. — Feathers of the chin and throat short, soft, broad, obtuse, and with the webs 

 blended. 



Middle toe and claw rather shorter than the tarsus measured from the beginning of scu- 

 tellae. Inner lateral claw reaching to the base of the middle. Black, with violet 

 reflection on the belly. Length, 19.20 inches; wing, 13 to 13.50 ; tail, 8 inches. 



C. americanus. 



Similar to the preceding, but smaller. Length, IC to 17 inches; wing, 11 to 11.50. 

 tail about 8 inches C. caurinus. 



