5R7 



to study West Iiuliaii, Cfiitial Aiucricaii, and evon tropical South AiiH'iicaii 

 forms, several members ol" wliicli spread as far north as tlie headwaters of 

 the Mississippi, aiul even Maine and Canachi. 



The tacts presenled in the hody of Ihis \vorl\ reiiardin^ the vaiialion in 

 size between Atlantic and Pacific coast examples of the same species, liiout,di 

 scanty, indicate the existence of some interesting laws of climatic variation, 

 which tend to confirm tlie generalizations estal)lished I »y Professor Baird * 

 ami Messrs. Allen and Ividgway as regards the avitiuina of Nortli America. 

 1 should, however, state that the fiict of variation in shape of t lie wings, 

 chiefly, however, variation in size, was forced u[)on me ijy a study of the speci- 

 mens themselves, without at the time having tin; views of our orifithologists 

 in mind. In all the species enumerated in the following list, the Colorado 

 examples (when the species have been found to occur there) and the Pacific- 

 coast individuals are larger, and in some cases with longer, more pointed 

 wings than in those from Labrador or the Eastern Atlantic States, and in a 

 few cases show a tendency to become lighter in color. 



SPECIES GROWING TO .V (JKEATER SIZE ON" THE PACIFIC TllAX ATLANTIC COAST. f 



Glaucopteryx cscsiata. Zerene catenaria. 



magnoliata. Phasianc orillata. 



Plemyria fluviata. Semiothisa californiata. 

 • Hydriomena californiata. granitata. 



Petrophora truncata. Aplodes ridjrifrontaria. 



prunata var. lugu- Geometra iridaria. 



brata nubilata. Tephrosia cauadaria 



Ochyria munitaria. Opisthograptis sul|)huraria. 



abrasaria. Anagoga pulveraria. 



Rheumaptera basaliala. Metrocampa perlaria. 



lugubrata. i\Ierina fervidaria. 



Hydria undulata. Endro[)ia bilinearia. 



Triphosa dubitata. Azelina hUbnerata. 



* " The Distribution and Migrations of Nortli American Birds," in Amer. Jourii. Sc. and Arts, xii, 

 Jan. and Marcli, 186G. See also J. A. Allen, Bull. Mas. Couip. Zoiil., ii, 1871, " On ludividiial and Geo- 

 graphical Variation among Birds, ic." ; and P. Pidgway, '• Ou the Relation between Color aud Geograph- 

 ical Distiibutiou in Birds as exhibited in Melanism and Iljperchromisni,'' in Amer. .Journ. Sc. Arts, iv, 

 Dec, 18(2, p. 454 ; v, Jan., 187:?, p. 39. 



t To this list may be added the following species belonging to other families of moths : Pkrophorus 

 einereidactylus, Draateria erechtea, Plusia Hochenwarthi, Agrotis islandica, and Lilhosia argiltacca. 



