-10- Harcourt Storm Petrel (Oceanodroma castro) I am quite sure I saw this species from about 5°S to 10°S. Due to the difficulty in separating this from Leach Storm Petrel, most birds were logged as Leach or next most similar species. The four individuals logged as Harcourt definitely lacked the dark feathers in the middle of the rump patch. Other that this I could find no difference in pattern, size, or behavior from Leach Storm Petrel. I must also state that these birds were not Oceanodroma tethys, or Oceanites oceanicus and were recorded as Oceanodroma castro by the elimination of the above two species. Leach Storm Petrel (Oceanodroma leucorhoa) White-rumped Storm Petrel sp. A very abundant species, perhaps one of the most abundant birds in the world. Recorded in every section of the cruise, being second only to Sooty Terns in total number of individuals. Large populations were found about 25°N, 13°N, 10°N, and throughout the equatorial doldrums. After crossing the doldrums, Leach became rarer until they finally disappeared at 17°S. Under good conditions two forms can be recognized in the field. The northern form, Oceanodroma l. leucorhoa, appears larger, darker, and has more white in the rump. The southern form which includes about three sub-species, is smaller, browner, and the amount of white in the rump varies considerably. Both forms were observed in all sections of the cruise track, but I think the northern form was dominant at 25°N, and the southern birds at 13°N, 10°N, and all of area "C". The large populations along the doldrums contained both forms of unknown ratios. All sub-species inter-mix freely at sea, and at least two races were collected from the same flock. The southern birds were in very worn plumage especially on head and throat while the northern birds were not. Ashy Petrel (Oceanodroma homochroa) This species evidently occurs south of its breeding range at least to the Revilla-Gigedo Islands in non-breeding season. It was observed in flocks of light and dark-rumped Leach and was distinguished by its smaller, chunkier appearance, fluttering flight, and light grey under-wing converts.