1907] Beebe: Geographic Variation in Birds. 21 



Any speculation as to the significance of these streaks and 

 spot would be of little value, based on this single experiment, but 

 the following facts should be mentioned in this connection, 

 whether or not future experiments give to them greater signifi- 

 cance than they now possess. Similar markings, the streaks and 

 pectoral spot, are present in the first winter plumage of Z. albi- 

 collis, being lost at the time of moult either into the first nuptial 

 or second winter plumage, while they are entirely absent in the 

 adult. 



In the closely related Spizella monticola, the tree sparrow, 

 a dusky pectoral spot is assumed with the first winter plumage 

 and is a permanent character of the adult birds of both sexes. 



Zonotrichia albicollis presents little variation throughout its 

 range which comprises the whole of eastern North America, and 

 no variations of subspecific value have been distinguished by 

 systematists. This lack of variation is probably due to the highly 

 migratory character of this bird, the breeding range being con- 

 fined chiefly to the region from New York and Michigan north- 

 ward to Labrador and Hudson Bay. Zonotrichia querula, the 

 Harris sparrow of the middle United States, is the species of this 

 genus which shows the largest amount of black in the plumage, 

 the entire crown, throat and part of the breast being of this color. 

 The close relation, almost congeneric, of Zonotrichia to Junco 

 demonstrates that predominating melanic coloring is at least pos- 

 sible in some members of this section of the Fringillidae. 



Part V. — Experimental — Scardafella. 



A — Normal Variation in Scardafella inca (Less.) 

 Inca or Scaly Dove. 



The genus Scardafella embraces a group of small doves 

 which extends as far north as southern Texas and Arizona and 

 south to Brazil. The forms at present recognized by systematists 

 are as follows : 



Scardafella inca, Southern Arizona and the Rio Grande val- 

 ley of Texas, south through lower California and other parts of 

 Mexico to Nicaragua. 



Scardafella i. dialeucos, known only from the boundary line 

 between Honduras and Nicaragua. 



Scardafella ridgwayi, Island of Margarita and coast of 

 Venezuela. 



Scardafella r. brasiliensis ,^ coast of Brazil, south at least to 

 Bahia. Nothing is known of its distribution in the interior. 



* This southern form has not as yet been separated, but for the purposes of this list 

 I have applied this term to the Brazilian birds. 



