500 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



of broad transverse scutella; middle toe more than two-fifths as long 

 as tarsus; outer toe much longer than inner toe, extending beyond 

 base (sometimes to middle) of penultimate phalanx of middle toe, 

 the inner not reaching much, if any, beyond base of the same or even 

 (in C. cyaneus and C. pygargus) falling short of the point; hallux 

 much shorter than inner toe, its claw equal to or longer than the digit; 

 claws rather slender, strongly curved, acute, distmctly graduated in 

 size, that of outer toe about two-thirds as long as that of hallux. 



Plumage and coloration. — Plumage soft, the remiges and rectrices 

 moderately rigid; feathers immediately behind auricular region small, 

 stiffish, with rounded tips, forming a "facial ruff," as in Striges and 

 genus Micrastur; bristles of loral region long, overlapping whole of 

 cere, very slender, cm-ved backward terminally, where projecting 

 above upper outline of cere." Coloration extremely variable, but 

 adult males with more or less bluish gray on upperparts (sometimes 

 almost uniformly so), the upper tail coverts usually white or partly 

 so; adult females and young without any bluish gray, the general 

 color brownish (at least on upper part), the underparts usually paler, 

 often striped with brownish, the upper tail coverts usually white or 

 partly white. 



Range. — Greater part of world, but wanting in northern Asia north 

 of 60° N. latitude, Oceania, and Galapagos Archipelago. (Many 

 species, but only one North and Middle American species.) 



Type. — Circus aeruginosus (Linnaeus). 



CIRCUS CYANEUS HUDSONIUS (Linnaeus) 



Marsh Hawk 



Adult male. — Head, neck, breast, and upperparts generally (except 

 the upper tail coverts) light neutral gray to deep neutral gray, washed 

 with brownish, especially on scapulars, tertials, and interscapulars, 

 often on the occiput and nape as w^ell; occiput slightly darker than 

 the crown and streaked with whitish, tinged with cinnamon; the 

 upper wing coverts neutral gray with dusky shafts; remiges similar, 

 but the five outermost primaries fuscous to fuscous-black on the inner 

 webs for their distal half (or a little less than half in some cases), occa- 

 sionally on the outer web also ; the inner primaries and the secondaries 

 with a broad, but rather indefinite subterminal band of dark hair 



^2 The pterylosis of Circus is said by Nitzsch to be very similar to that of 

 Milms, Pernis, and Astur, differing chiefly in the oblique position of the outer 

 branch of the inferior tract (ventral pteryla), which does not run parallel to the 

 main stem and is therefore rather more connected with the latter anteriorly; a 

 distinct oval apterium before the ear and beneath the eye; remiges 24-25; there 

 is one pair of inguinal powder down patches, ascending on each side of the dorsal 

 portion of the spinal tract to the shoulders. 



