70 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4TH SER. 
In some instances I have included observations made by Mr. 
Alexander Sterling Bunnell and Mr. Beck while on the Expe- 
dition of the California Academy of Sciences to the Revilla 
Gigedo Islands, Mexico, in the schooner Mary Sachs. The 
Expedition left San Francisco April 25 and returned August 
13, 1903. It was planned and organized by myself, as Direc- 
tor of the Museum of the Academy. Unfortunately, all the 
specimens obtained were destroyed in the San Francisco con- 
flagration of April, 1906. 
During the autumn of 1911 I visited the principal museums 
of the United States and examined the albatrosses, petrels, and 
diving petrels in their collections. Many specimens have been 
lent to me by museums and individuals for comparison, and 
acknowledgment of this assistance has been made in my intro- 
ductory remarks. 
The specimens of albatrosses and petrels in the museum of 
the California Academy of Sciences number over two thou- 
sand, and at the time of this writing constitute the largest col- 
lection of these birds in the United States. 
To bring to the work in hand fresh impressions of the bird 
life of the sea, I revisited Monterey, California, in December, 
1912, and made numerous excursions in a gasoline launch to 
the ocean off Point Pinos. 
MEASUREMENTS.—With the exception of the few diving 
petrels, treated in part V, all the specimens were measured by 
my young friend, Mr. Edward Winslow Gifford, formerly 
Assistant Curator of the Department of Ornithology in the 
California Academy of Sciences and now Associate Curator 
of the Anthropological Museum of the University of Cali- 
fornia. Over thirteen thousand measurements were taken by 
him, forming a series unparalleled in the albatrosses and 
petrels. Unless otherwise stated, all measurements refer to 
specimens in the collection of the California Academy of 
Sciences. In measuring the wing from the carpal joint to the 
tip of the longest primary, the primaries were flattened against 
the surface of the rule, giving a dimension greater than the 
chord. The length of the culmen is the chord of the exposed 
culmen, and was taken with dividers. The depth of the upper 
mandible is the distance between the base of the exposed cul- 
