282 CIRCUS CYANEUS. 



and bent downward to a point at about one half the height of the keel. The marginal in- 

 dentations are large in the young stages, but are always inclosed, becoming smaller in the 

 more adult birds. 



GENUS I. CIRCUS. THE HARRIERS. 



GEN-. CH. Bill, not tony, well curved, with the cutting edge of upper mandible slightly lobed. Tarsus, long and nearly 

 naked. Tail, long, but is not equal in length to thewmgs which are considerably elongated. Lower portion of face, sur- 

 rounded by a ruff. 



Members of this genus not only resemble the owls in having a ruff, or facial disk, but the ear cavities nre large and the 

 plumage is somewhat downy. The leg'is strikingly long and the tarsus is naked to the heel behind, but is slightly feath- 

 ered in front. Four outer quills are incised on the inner webs. The trachea is flattened throughout. The sterno-trarhe- 

 alis is short, having its origin about '25 from the larynx, and there is a slender bronchial is extending overall the half rings, 

 but no other laryngeal muscles. The tympaniform membrane is present and although there is a thin os tran<ve,'sale, it 

 does notsupport a semilunar membrane. The walls of the oesophagus are thin; this is at first nearly strniyjit, then is dilated 

 into an oblong crop near the middle, after which it is again straight until it opens into a rather small proventrieulus with 

 simple, oval glands arranged in a zonular band which measures TOO in cyancus, from which this and the following dimen- 

 sions were taken. The stomach is of medium size, somewhat globular in form, with thin but soft walls and is lined with n 

 soft inemhrane. The fold of the duodenum is long, measuring 3'50, inclosing a narrow pancreas which extends it-son 

 tire length. The coeca are merely represented by slight swellings on either side of the intestine. The spleen is an ellipti- 

 cal body lying directly on the proventriculus. Both lobes of the liver are equal in size and are short and thick. The heart 

 is large, bent slightly to the right and not very pointed. Sexes, not similar in color. There is but one species within oui 

 limits. 



CIRCUS CYANEUS. 



Marsh Hawk. 

 Circus cyaneus BOIE, Isis; 1822, 549. 



DESCRIPTION. 



Sp. CH. Form, long and slender. Size, medium. Sternum, rather stout, with themarginal indentations varyingwith 

 age. Tongue, short, not very fleshy, and about the same width for nearly its entire length, then abruptly rounded but not 

 bifid. Bill and claws, not long. 



COLOR. Adult male. Above, including upper wing coverts, side* of head, and breast, pale bluish-ash, becomingruf.ms 

 on the back of the head and upper neck. Upper tail coverts, white. Wings, brown, edged on the outer webs with ashy 

 and barred with darker. Two middle tail feathers and outer webs of remainder, bluish-ash, and inner webs, ruf m-;, li:-.rred 

 across the feathers with dark-brown. Under portion of tail, silky white. Beneath, including under wiagnnU tailcutrrts 

 and'tibia, white, spotted with pale reddish. Iris, pale yellow. 



Adult female. Above, brown, with the feathers more or less ashy, edged on the head and neck and spotted on the re- 

 maining portion with rufous. Beneath, including under wing and tail coverts, reddish-white, darkest on thetibca, with 

 every feather having a central spot of reddish-brown, broadest and darkest on the breast, narrower on the neck, smaller, 

 rounder and more decidedly rufous on the posterior portions and tibea: otherwise as in the male. 



Young male. Similar to the adult female but decidedly darker above, where there is no trace of ashy but there is more 

 rufms on the spottings and edgings. Beneath, very dark rufous, not much spotted, often being wholly immaculate on the 

 posterior portion and tibea. Iris, brown. 



Young female. Quite similar to the young male but somewhat lighter throughout, especially below, where the dark- 

 ening of the rufous is only seen on the tibia. 



Nestlings. Are at first covered with a reddish down, then gradually assume the plumages last described. Iris, brown. 

 Bill, bluish-black, cere, greenish, feet, yellow, and claws, brown, in all stages. 



OBSERVATIONS. 



There appears to be considerable variation in specimens, some being darker than others and more heavily spotted, but 

 this may be due to age and sex. Known from all other species by the peculiar ruff about the face combined with the white 

 of the upper tail coverts, which i-i noticeable in all stages. Distributed, as a summer resident, throughout North America. 

 Constantly resident in the more southern portions. 



