164 CALIFORNIA ACADEMY OF SCIENCES __ [Proc. 4rm Ser. 
age. The majority of the specimens obtained at sea between 
the 5th and 9th of October are in full moult. In three of eight 
specimens secured on the 15th and 19th of November renewal 
is still in progress. 
During the Expedition’s visit to the petrel colonies of the 
San Benito Islands, on the 14th, 15th, and 17th of July, 1905, 
five fresh eggs of the “Socorro Petrel’’ were obtained from de- 
.serted burrows of Cassin’s Auklets. The burrows were situ- 
ated in earthy spots, and were about three feet in length and 
had one or two turns. The egg in each case was deposited on 
the bare ground at, or near, the end of the burrow. The season 
was apparently not far advanced, for pairs without an egg were 
occupying burrows. The duties of incubation were shared by 
both sexes; in two instances the male was setting and in three 
the female. 
The last captures of the southward voyage (a female and six 
males) were made on July 22, about latitude 22° 25’ N., longi- 
tude 112° 40° W. In one of the males the upper tail-coverts 
are white and in the female and the other males they are dark. 
All exceed the size ascribed to “O. kaedingi.” 
During a cruise below the Galapagos Islands, three speci- 
mens, having white upper tail-coverts and dimensions corre- 
sponding with the larger northern specimens, were shot on 
June 11, 1906, in latitude about 4° 20’ S., longitude 93° 30 W. 
On both the Atlantic and Pacific this species appears to extend 
its exodus-migration into the Southern Hemisphere.* 
On the homeward voyage in 1906 eighteen specimens with 
white upper tail-coverts were taken as follows: Five, October 
5, latitude 14° 28’ N., longitude 107° W.; three, October 8, 
latitude 14° 40 N., longitude 109° W.; two, October 9, lati- 
tude 14° 11’ N., longitude 109° 20° W.; three, November 15, 
latitude 33° 7’ N., longitude 134° W.; five, November 19, lati- 
tude 35° 40’ N., longitude 133° 14° W. With one exception, 
none exhibits the dimensions of the “O. kaedingi” series. 
5, Atk; 1902, v. 19, p. 293; Nicoll, This, 1906, p. 667; Murphy, Auk, 1915, v. 32, 
