48 



CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



less degree than shown by the average Baja Cahfornia speci- 

 mens. One female (No. 1941 C. A. S.) from the latter 

 region, has no dark edgings on the under tail-coverts — a con- 

 dition perhaps due to wear. 



As shown by the measurements of Table VIj p. 114, there 

 are but slight differences between average specimens from 

 the two localities. The Galapagos birds average larger in 

 length of culmen and length of middle toe, while the Baja 

 California birds average larger in length of wing and length 

 of tail. The measurements of the two series, however, over- 

 lap, and in the absence of constant color characters, it is im- 

 possible to find in the slight differences in the average meas- 

 urements any basis for specific distinction. 



Three young males from the Galapagos Islands (Nos. 

 1893, 1902, and 1930 C. A. S.) have down adhering to 

 some of the juvenal feathers, considerable gray down on the 

 throat, and primaries not full grown. Many of the scapulars, 

 interscapulars, tertials, and wing-coverts are marked termi- 

 nally with a narrow light-brown edge, and subterminally with 

 a narrow dark-brown or black bar. The tarsi are very much 

 swollen near the suffrago. This swelling, however, disap- 

 pears as the birds grow older. In dried skins the young have 

 the naked parts of a much darker color than the adults. 



In two older specimens (Nos. 1891 and 1892) still show- 

 ing traces of down on the rectrices, the brown edgings are 

 yet present on the wings, but have disappeared from the back, 

 having evidently been removed by wear. New feathers are 

 appearing in the back, head, neck, and breast of these 

 two specimens. The new feathers have no brown margins, 

 but appear indistinguishable from those of adults. Inasmuch 

 as the birds still show traces of neossoptiles, it is assumed that 

 this moult is postjuvenal and not prenuptial. 



The measurements of the five young birds are given below. 



MEASUREMENTS OF YOUNG BIRDS (in millimeters) 



