460 The American Naturalist. [June, 



the range of migration and the tendency to produce geo- 

 graphical races, for otherwise this coincidence could not be 

 explained. So having found that those species undertaking 



not. 





■ give 



to local 



long migrations < 



varieties, we must conclude that the process of taking exten- 

 sive migrations is a check upon the tendency to produce geo- 

 graphical varieties. But in order to round off further deduc- 

 tions, we must first determine whether species which do not 

 migrate extensively have a greater tendency to geographical 

 variation than those just considered ; and this assumption 

 will be strengthened by a comparison of the species in the fol- 

 lowing List III with those in Lists I and II. 



III. Species with a short < 



nigration range. 



Alcidse. 



Rhynchops. 



Anhinga. 



Phalacrocoracidae (e 



Pelecanidse. 



Phasnicopterus. 



Plataleidx. 



Jbididss. 



Ciconiidse. 



Ardeidae (most). 



AramMse. 



Rallidx (most). 



Hzernatopodidx. 



Tetraonidse. 



Phasianidse. 



Cracidse. 



Falconidse (most). 



Strir prtotincola. 



PsittacidsB. 

 Cii.culidte. 

 Trogonidse. 

 Momotidse. 

 Alcedinidse (most). 



Picidse (most). 



Caprimidgidx (mos 



Trochilida (most). 



Cotingidse. 



Tyrannidte (most). 



Alaudidx. 



C&rvidse. 



Ideridm (most). 



Fringillidte (most). 

 f Euphonia. 

 [ Piranga (most). 



Ampelidse. 



Vireonidfe (most). 

 Coerebidte. 



Mniotiltidse (a few). 

 Cinclidse. 



Troglodytidse (most 

 Certhiidw. 

 Parkhi:. 

 Polioptila. 

 Turdidx (most). 



