﻿FIELD AND FOREST. 41 



considered, L. tcphrocotis is the next most Southern, is the next in size, 

 (at least is not larger than var. littoralis,) and has the least ash on the 

 head. " The first point is reasoned from the fact that Mr. Aiken 

 found littoralis far less numerous in Colorado than typical tephrocotis, 

 and therefore supposed that it must be a more Northern bird, not 

 migrating so far South in winter. [See Mr. Aiken's remarks, copied by 

 Mr. Allen in foot note, on page 248.] The comparative rarity of this 

 form in Colorado is not to be thus accounted for, however, but is due 

 to the fact of its being a more Western bird, only stragglers to the east- 

 ward of its main range, mixing and associating with the main body of 

 tephrocotis. In the same manner tephrocotis, itself, becomes rare west- 

 ward, where, through the Great Basin and Sierra Nevada, the main 

 body of littoralis migrates southward. The differences, then, between 

 these two races, if depending solely on climatic considerations, are 

 governed by the longitude and not the latitude, of their breeding 

 habitat. 7 As to tcphrocotis being " next in size (at least is not larger 

 than var. littoralis, )" Mr. Allen's own computations show that is the 

 larger of the two, except as regards the length of the tail. 8 



Admitting that tephrocotis " has the least ash on the head," how 

 can this fact be attributed to climatological influences when littoralis, 

 as stated, is not more Northern in its distribution, and when griseinu- 

 cha, the most Northern of all the forms , has less gray on the head than 



fornia. On the same page we are astounded by the inforformation that C. santa 

 cruzi and C. elegans are " the Southern forms of C. flavi ventris /" 



In the " Ornithological Reconnoissance " [Bull. Muss. Comp. Zoology, Cambridge, 

 III, No. 6, July 1872,] it is stated, on page 115, that "passing to the plains, proper, 

 the faded aspect of all the birds is strikingly noticable, especially in species that range 

 across the Continent." As an illustration, several very proper examples are mentioned ; 

 but with them are included the " 'Cassini' type of Peitccea czstivalis," the fact ofthe 

 case being that Peuccca cassini is a very distinct species, possessing well defin ed 

 characters which should distinguish it at a_ glance from P. aestivalis, which has, in 

 the same region, a Western race. The theory of certain climatic variations in the 

 genus Pipilo, is expressed (page 1 17,) in the following terms: "In Mexico, P. 

 megalonyx is well known to grade through P. marcronyx into P. macu/atus." We 

 are not aware that this fact was " well known " to any onebut Mr. Allen, and he will 

 probably now acknowledge himself mistaken so far as P. marcronyx is concerned. 



6 My own measurements of these two forms being from 203 dried specimens, 

 should, as a matter of fairness, be taken for comparison ; they indicate a still greater 

 difference in average length of wing in favor of australis, the wing of the latter av- 

 eraging .08 more; the difference in the length of the tail, however, is somewhat re- 

 duced, the discrepancy amounting to only .12. 



