195 



European species (P. tridactylns L.). The latter lias two well-marked 

 climatic races — a large, very liijlit colored northern one (var. crisso- 

 leucns Brandt) and a smaller, darker southern one (var. trklactyhis L.). 

 The former has the back white longitudinally, somewhat like our var. 

 dorsalis, l)ut differs very decidedly in other respects. One is hardly 

 justified in saying that " all the species of this genus are unquestion- 

 ably modified derivatives of one circumpolar stock" (see Coues, Key, 

 p. 19i) ; and the statement that " the American seem to have become 

 completely ditterentiated from the Asiatic and European" is equally 

 objectionable. A comparison of dorsalis and Aincricanus with the 

 Old World forms, shows plainly that the amount of differentiation 

 scarcely comes up to the qualifications of a difference of race. A 

 comparison of arctkus with the rest also shows that bird to possess 

 evei'y requirement of an independent, and truly distinct species. 



149. SPHYRAPICUSTHYROIDEUS (Cass.). Though this species 

 is not given in Mr. Allen's list, he nevertheless collected it iji Colo- 

 rado, but the specimen being in immature plumage was identified as 

 S. nuchalis. 



155. GLAUCIDIUM (PASSERINUM, var. CALIFORNICUM?). 

 Not having seen the specimens of the pygmy owl collected by Mr. 

 Aiken iu Colorado, I cannot say positively that they belong to this 

 species. They are quite as likely to be G. ferrugineum, which was 

 collected in Arizona by Lieut. Charles liendire, U. S. A. (See Am. 

 Nat. vi, 370, and Coues' Key, p. 206.) 



178. MELEAGRIS GALLOPAVO. Mr. Aiken has not informed 

 me whether tlie Colorado bird is var. gallopavo, extending northward 

 along the mountains, or the eastern form (var. sylvestris) reachin" 

 westward to the mountains by following the wooded valleys of the 

 rivers across the plains. It is most likely, however, to be the former. 



187. DKMIEGRETTA sp? This is v^obtihly the D. Ludoviciana. 

 See Allex, Bull. Mus. Comp. Zool., Vol. iii, No. G, p. 153. 



237. LARUS sp. ? This gull is probably the L. argentatus, var. Cal- 

 ifornicus, which I found breeding very abundantly at Pyramid Lake 

 Nevada, and less numerously at Great Salt Lake, on Carriugton 

 Island. 



It is difficult to see Dr. Coues' reasons for referring this form to 

 Delaicarcnsis, since it has no points at all iu common with the latter 

 species, from which it is perfectly distinct, though clearly referrible 

 to argentatus. 



