176 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4tu Ser. 
Two Carnegie Museum specimens (Nos. 22312 and 22316, 
Sept. 7, 9, 1896, San Benito Is.) are in natal down, with the 
region of the throat bare. In one the secondary down is well 
advanced on the body and jugulum; in the other it is backward. 
The color of the primary down is hair brown and that of the 
secondary chaetura drab. Fresh specimens would probably be 
grayer. The wearing off of the primary down, exposing the 
darker secondary down, was likely the cause of the change of 
color with age noted by Mr. Adriaan Van Rossem.* 
Although the Academy’s series is a long one, only the in- 
terval between May 27 and September 14 is represented in it. 
The trend of the moult, however, is fairly well indicated. In 
nineteen July specimens from the San Benito Islands, the 
renewal of the first primary in one specimen and of a single 
rectrix in another is the only obvious feather growth in prog- 
ress. In eighty July specimens taken at sea, one has the second 
primary of the right wing and eleven have the first primary 
of both wings still in the sheath stage. One of the eleven speci- 
mens is also renewing some feathers on the breast, crown, 
cervix, and upper back, and another, two rectrices. Five other 
of the July specimens are restoring each a single rectrix, a 
sixth is restoring two rectrices, and a seventh, three. As this 
species is a late breeder, these tardy restorations probably be- 
long to the fag-end of the moult. Five May and five June sea- 
collected specimens appear to be stationary in their plumage. 
Of forty taken at sea in August, only six, obtained after the 
third week, have growing feathers. Two of these specimens, 
at least, seem to be at the beginning of the moult. A couple 
shot on the 2nd and 14th of September have apparently not 
‘commenced moulting. 
The measurements in millimeters of ninety-three males and 
fifty-seven females are tabulated below. 
Middle 
Sex Wing Tail Culmen Tarsus Toe and 
Claw 
Maximum.......... ofl 186 92 17.6 33.5 31.1 
Mitnimcianties senor ot 167 78 14.5 29.3 27.3 
Mien nett nena of 176 84 15.8 31.2 29.4 
Maximum.......... $e} 186 93 16.6 32.5 30.5 
Minimum.......... 12] 170 78 14 28.9 27.4 
Mean eer eae 9 178 86 15.6 30.7 29.1 
1 Condor, v. 17, p. 77. 
