222 



NORTH AMERICAN BIRDS. 



Subgenus N I S U S , Cuvier. 



Accipiter, Brisson, 1760.1 



Nisus, CuviEii, 1799. (Type, Falco nisus, Linn. ; A. fringillarius (Ray), Kaup.) 



Jerax, Leach, 1816. (Same type.) 



Cooperastu?; Bonap. 1854. (Type, Accipiter cooperi, Bonap.) 



Hieraspiza, 1844, Jeraspiza, 1851, and Teraspiza, 1867, Kaup. (Type, Falco tinus, Lath.) 



Hieracospiza, Agass. (Same type.) 



Urospiza, 1845, Urospizia, 1848, and Uraspiza, 1867, Kaup. (Type, Sparvius cirrhocepha- 



luS, ViEILL.) 



Erythrospiza, Kaup, 1867. (Type, A. trinotatus (TEiMM. ?) 

 Microoiisus, Gray, 1840. (Type, Falco gabar, Daud.) 

 Nisastur, Blas. 1844. (Same type.) 



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

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

 markable strength and unsurpassed daring. They differ from the species 



26588, f, 



Nisus fitscus. 



Nisus cooperi. 



of Astur mainly in less robust organization. The species are very numerous, 

 and most plentiful within the tropical regions. The Old World possesses 

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



1 Not admissible as having been bestowed by a non-binomial author, and of prior date to the 

 commencement of binomial nomenclature. 



