182 CALIFORNIA ACADEMY OF SCIENCES. 



and mammals. Next most common is the throat j^atch 

 which is not strictly but mainly confined to the ptery- 

 lograpliical region lying between the lower jaw bones 

 and extending downward along that line. A transverse 

 stripe on the frons either of light or dark is very com- 

 mon, as in Melanerpes formicivorus bairdi, Geothlypis 

 trichas, Dendroica dominica, etc. So also a transverse 

 band on the nape is common as in Cyanocitta cristata, 

 DoUchonijx oryzimrufi. A median line on the head is com- 

 mon, as in Sturnella magna, Reguhis mtrapa, Tyrannusi 

 tyrannies, the young of Habia, and many others. A con- 

 trasted transverse band terminating the throat patch is 

 common, as in Hesperocichla na-viu, (Jyunocitti/ cristata, etc. 

 In fact, whenever the breast has any diversity of marking 

 a breast patch of some sort is the general rule. The belly 

 is only A-ery exceptionally marked, and then either 

 simply streaked or barred, or more rarely, spotted as 

 in Colaptes, but the flanks are usually marked either a 

 darker shade than the belly or streaked or barred. The 

 under tail coverts are frequently streaked, barred, or 

 colored quite differently from the belly as in the cat bird 

 {G(d.eoscoptes carolinensis) and Californian towhee {Pipilo 

 fuscus criHS(dis). The rump patch is very often 

 marked by some conspicuous color as in the yellow- 

 rumped warbler {Dendroica coronata) and the flicker 

 {Colaptes aundux). The wing and tail markings are 

 strikingly varied and characteristic of species. 



In accounting for these patches of color and their 

 distribution in diverse patterns it will be necessary, it 

 seems to me, to abandon wholly or largely internal laws 

 of growth as explanation. Dr. Harrison Allen has pub- 

 lished a paper on the Distribution of Color Marks of the 

 Mammalia* in which he elaborates the view that the 

 distribution of pigment is favored by the presence of 



* Proc. Acad. Nat. Sci. Phil., 18S8. 



