186 University of Califonna ruhlicatio}is in ZooJofjjj. [Vgl. 7 



'"The finch of Guadalupe Island {C. amplits) shows more 

 stability in its coloration, hut even here we often fnd birds 

 varying from the normal. Of seventeen males before me, nine, 

 or over one-half, are more or less yellow. In two of these the 

 rump, head, and breast are clear lemon yellow, in a third the 

 feathers are about equally red and yellow, of a pale washed-out 

 look. The remaining six have a few yellow feathers irregularly 

 mixed with the crimson. The proportion of yellow birds which 

 really occurs is probably less than the above figures would indi- 

 cate, as this series was selected somewhat with a view to getting 

 the abnormal examples." 



Although peculiarities in coloration are used as diagnostic 

 characters of the above two insular forms (Ridgway, 1901, pp. 

 141, 142), there are also in each case structural features (pro- 

 portions of bill, etc.) which alone differentiate them from each 

 other and from the mainland form. 



The climate of the San Benito Islands is, according to pub- 

 lished accounts, hot and arid, that of Guadalupe Island, fairly 

 cool and semi-humid. 



It would seem from what is shown by Table II, as well as 

 from the additional data given immediately above, that neither 

 humidity or temperature, nor both (that is, climate) can be 

 called into account as an actuating cause of the appearance of 

 the yellow "sports." It is of interest to note that of the native 

 passerine birds of the Hawaiian Islands, which are brightly 

 colored, seven are brilliantly red, and some twenty-one are more 

 or less yellow^ or orange. These are all quite surely themselves of 

 exotic origin, though so remotely that their affinities are not 

 clearly a])parent. According to Gadow (fide Knowlton, 1909, 

 p. 809) the Drepanidae, to which family most of the brightly- 

 colored Hawaiian birds l)el()ng, are probably dei'ived from the 

 American family Coerebidae (honey creepers). The repre- 

 sentatives of the latter family many of them have much yellow 

 in the plumage ; but none of them are red. 



Among various species and families of birds in Xoi-th 

 America climate has no evident effect on the i)redominanc(' of 

 these colors. Both red species and yellow species occur in humid 

 and arid, hot and cold, regions. There ai-e, however, most of 

 both in warm, humid regions. 



