142 CALIFORNIA ACADEMY OF SCIENCES. 



an attempt will be made later to explain this instance 

 in accordance with it. 



Enough examples have now been given, I trust, to 

 show that, as a rule, the shade of color which we agree 

 to call the primitive color is a composite which, when 

 more or less completely resolved into its component 

 elements, gives the two specialized tints of the species 

 or genus. A word may be said as to the criterion of a 

 general and special color. In the first place, in accord- 

 ance with the law of the correspondence of the onto- 

 genic and phylogenic series, or the tendency of the indi- 

 vidual to repeat ancestral stages, if the young differ from 

 the adult in color (unless the latter be a degenerating 

 form), it will represent an earlier and more generalized 

 type. Furthermore, in an adult male bird the color 

 which is spread over the greater part of the body is 

 ordinarily the generalized color, while the detailed 

 markings represent the more specialized hues. This is 

 directly analogous to the geographical distribution of 

 animals. If we have two allied species of animals, the 

 one found upon the mainland, the other upon an island, 

 or the one spread over a wide area and the other in a 

 limited section, we should conclude that the species 

 having a restricted range had sprung from the species 

 having a wide range. More especially would we con- 

 clude this if the limited form had some mark of superi- 

 ority to the other. It is found that among birds the 

 limited markings are, as a rule, of a purer or more 

 sharply defined color than the body color. Notice, for 

 instance, the crest of the kinglets or the breast of the 

 rose breasted grosbeak. In cases of high specialization, 

 as with the orioles and tanagers, for instance, the gen- 

 eralized colors may be completely superseded by the 

 specialized, in which case the female and young, alone, 

 would show anv trace of them. 



