180 riiiversitji of Califoniia Publications in Zoology. [Vol.7 



region and chest. In "high plumage" the sides of the head and 

 neck, the whole dorsum and top of head, and even the lower 

 breast, belly and crissnm, may be pervaded with a tint of those 

 parts always colored. The remainder of the plumage is of the 

 hair-brown and grayish-white pattern displayed on all parts of 

 the female. 



In the large series of males of the California linnet, leaving 

 out the rare examples which are distinctly yellow or orange, 

 striking variation is shown in the tint of the red. But arrange- 

 ment of the component examples by date, from September to 

 July, shows this variation to parallel the lapse of time beyond 

 the fall molt, and to be altogether due to the effects of wear. 

 There is no spring molt; and the notion that an influx of new 

 pigment into the feather towards spring serves to produce the 

 bright colors of the nuptial dress is. of course, without founda- 

 tion. In the fresh fall plumage the red is of a conspicuous pink- 

 ish cast (burnt carmine of Ridgway's Nomenclature of Colors, 

 1886 edition) ; there is thereafter a gradual change through crim- 

 son, until by summer a brilliant poppy red is displayed. 



Attention may here be called to the fact that the brilliant 

 hues of the nuptial plumage are thus, in reality, determined in 

 the forming feathers at the post-nuptial (or annual) molt, sev- 

 eral weeks after the season of mating, instead of immediately 

 preceding. This fall molt period is generally considered (as by 

 bird-fanciers and poultry-raisers) to be the time of the year 

 when the general vitality of the bird is at its lowest ebb. More- 

 over, the organs of reproduction at this time are reduced in 

 size and in the sexual function to a quiescent condition. It 

 would seem, therefore, that the production of the brilliant nup- 

 tial plumage is not in the linnet coincident with a period of ex- 

 cessive sexual vigor, as some applications of a current theory 

 seem to demand. (See Cunningham, Sexual Dimorphism in the 

 Animal Kingdom, 1900. pp. 36-44.) It is, however, clearly 

 anticipatory; and here we find manifestation of a most delicate 

 structviral complex, so adjusted, as pointed out in the next suc- 

 ceeding paragraphs, as to bring about through purely extrinsic, 

 physical agencies, a "nuptial" brightening of dress at the season 

 of courting, seven to nine months later. 



