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NORTH AMERICAN BIRDS. 



Subgenus N I S U S . Cuvier. 



AccipiUr, Brisson, 1760.' 



Nism, Cuvier, 1799. (Type, Falco nisiis, LiNX. ; A. fringiHarius (Ray), Kaup.) 



Jerax, Leach, 1816. (Same type.) 



Cooperasttir, BoNAi". 1854. (Type, Accipiter cooperi, Bon.^p.) 



Ilieraspua, 1844, Jcraspiza, 1851, and Teraspisa, 1867, Kait. (Type, Falco Units, Lath.) 



Hkracospiza, Agass. (Same type.) 



Urospiza, 1845, Urospizia, 1S4S, aiul Urcuspiza, 1867, Kai'?. (Type, Sparvins cirrhocepha- 



lus, VlEILL.) 



Erythrospiza, Kaup, 1867. (Type, A. triiiolalm (Temm. ?) 

 Micronisus, Grav, 1840. (Type, Fako gahar, Daud.) 

 Nisastur, Bla.s. 1844. (Same type.) 



The species of this subgenus are generally of small size and slender form ; 

 but witli a graceful and apparently delicate structure they combine re- 

 markable strength and unsurpassed daring. They differ from the species 



T^sus fusnts. 



Nisus cooperi. 



of Astur luaiuly in less robust organization. Tlie species are very numerous, 

 and most plentiful within the tropical regions. The Old World ])ossesses 

 about thirty, and America about fifteen, nominal species. Several South 



• Not admissible as liaving been bestowed by a uonbincimial author, and of prior date to the 

 commencement of binomial nomenclature. 



