NATURAL SCIENCES OF PHILADELPHIA. 1 1 1 



Subfamily CIRCmjE. 

 A ruff of short, stiff, close feathers around the face, as in the owls. (Strigidu 



Genus CIRCUS, Lacepede. 

 Fine bristly feathers of the lores extending upwards above the cere. Bill 

 rather weak, much compressed; upper outline of the cere forming an ascend- 

 ing plane, somewhat arched at posterior end. Nostril oval, horizontal ; super- 

 ciliary shield inconspicuous, though prominent. Tarsus more than twice the 

 length of middle toe; very slender, the icutellaa distinct. Wing long. 



1. Third and fourth quill equal and longest; second equals fifth; first 

 shorter than sixth; second, third, fourth and fifth sinuated on outer 

 webs; inner webs of outer four emarginated. 



C. hudsonicus, (Linn.,) Vieill. 



Subfamily ACCIPITRIN.E. 

 No ruff. 

 A. Accipitres. Bill much as in last; but less compressed and higher through 

 the base ; height at base exceeding chord of the culmen, the cere on top much 

 ascending basally; commissure anterior to the festoon deeply scolloped. 

 Nostril broadly ovate, obliquely horizontal. Toes very long. Wing 

 short ; fourth quill longest; second shorter than sixth ; first equal to 

 or shorter than the tenth ; outer quill bowed ; second to sixth (inclu- 

 sive) sinuated on outer webs ; inner webs of outer five emarginated. 

 Tail long, but not equal to wing. 



a. Astur, Lacepede. Upper half of tarsus feathered, the feathering scarcely 



interrupted behind, where the bare space is covered with small circular 

 scales ; base of toes and lower part of tarsus with only irregular small 

 scales A. atricapillus, (Wils.,) Bonap. 



b. Accipiter, Brisson. Less than one-third of the tarsus feathered below the 



knee; transverse scutellae continuous all along the toes, ar.d tarsus 

 in front. 



1. Middle toe longer than bare portion of tarsus in front; scutellffl of 

 tarsus rery distinct A. C'ooperi, (Bonap.,) Gray. 



2. Middle toe shorter than bare portion of tarsus in front; in adult birds, 

 scutellse of tarsus fused into an apparently-continuous plate, but in the 

 young distinct A. fuscus, (Gmel.,) Bonap. 



| Bill stouter and less compressed than in preceding; feet robust: third to 

 fourth quill longest. 

 A. Tarsus closely feathered to the, toes. 



a. Aguil.r. Toes (except terminal joint) with only small scales. 



Genus AQUILA, Moehring. 



Feathering of tarsus not interrupted behind ; middle toe more than half as 

 long as tarsus. Upper outline of cere parallel with lower Nostrils narrow, 

 oval, obliquely vertical ; fourth quill longest; first shorter than seventh or 

 eighth ; five to seven quills sinuated on outer webs ; five or six emarginated 

 on inner. Feathers of the occiput and nape lanceolate* 



Genus ARCHIBUTEO, Brehm. 



Feathering of the tarsus interrupted behind by a narrow bare strip, expos- 

 ing the knee ; middle toe less than half as long as the tarsus. Upper outline 

 ofcere ascending basally. Nostril broadly oval, obliquely horizontal ; fourth, 

 or third and fourth quills longest ; first shorter than seventh ; second to sixth 

 (inclusive) quills sinnated on outer webs ; four or fivo emarginated on inner 

 webs. Feathers of occiput and nape normal. Chin with a slight tuft oJ 

 bristly feathers projecting forward. 



* Including all the European, as well as the American species. 



1870.] 



