the light phase one from Hawaii or the dark phase population from the Line Islands or French Polynesia. This conclusion is inescapable. Further work will be necessary to tell which population is from an out- side area or if in fact both populations are from the west with the eastern Pacific birds intermingled with these populations. Juan Fernandez Petrel (Pterodroma e. externa) Juan Fernandez Petrels were common only along 105°W. Earlier in the summer Gould found them commonly along the 98°W meridian suggesting a westward movement in August. This could correspond with the increase of this species in the central Pacific during late summer. It should be remembered that at the same time they are common in the eastern Pacific (August) they are also common in the central Pacific - a range of over 2000 miles. Collared Petrel (Pterodroma leucoptera brevipes) Collared Petrels are easily separated from other forms of small Pterodroma by the dark underwing border and black cap which extends down the neck. Hydrobatidae In the past, identification of the dark storm petrels with white rumps has been difficult. This is due in part to the fact that on most trips only one species is seen, namely Leach's Storm Petrel. On this trip most of the species of this group were observed, and after watching them in the field and checking study skins I feel that I can identify a good many individuals in the field by size and plumage charac- teristics. The following is my identification key to the "white-rumped" storm petrels of the central and eastern Pacific. I. Size: Largest to smallest Leach's - Oceanodroma leucorhoa Harcourt's - Oceanodroma castro