-6- Black-winged Petrel 15 (Pterodroma hypoleuca nigripennis) Bonin Island Petrel ? (Pterodroma hypoleuca hypoleuca) 4 White-winged Petrel (Pterodroma leucoptera) 1 These small Pterodroma were almost without exception recorded south of the South Equatorial Current in the Central Pacific Water Mass. This in- dicates their preference of a distinct water type. These forms will al- ways pose identification problems and unless the individuals are close and viewed under good conditions, specific designation is hardly more than a guess. The sightings referred to Bonin Island Petrels ? could well have been the race P.l. brevipes of the White-winged Petrel. At least 13 other sightings were recorded simply as small Pterodroma. Cooks Petrel 1 (Pterodroma cookii) Excellent views of a single individual were made on 1 April at the mouth of the Gulf of California. I am reasonably certain I saw none of these in the concentrations of similar small Pterodroma near 20°S. Harcourt's Storm Petrel (Oceanodroma castro) ? 8 Leach's Storm Petrel (Oceanodroma leucorhoa) 178 Galapagos Storm Petrel (Oceanodroma tethys) 15 unidentified white-rumped storm petrels 213 Except for abundant coastal species, white-rumped storm petrels were second in numbers only to the Sooty Tern. High densities were recorded in both the North and South Equatorial Currents. Numbers dropped off consid- erably south of 5°S latitude. Despite the elaborate "Keys" and other identification aids proposed by Project members, a white-rumped storm petrel at 100 yards is just that! The fantastic amount of variation in rump patches of Leach's easily covers the ranges of this character of all other white-rumped species. In time of molt Leach's tails are not necessarily forked; they occasionally may dabble their feet as do Wilson's; and their flight may be as erratic or as slow as any of the other species, depending upon their mood. I still maintain that the "Crossin Method" * of field identification of this group is the only sure way. By this method 125 specimens of white-rumped storm petrels were taken during the present cruise. Examination of this large series only emphasizes the folly of attempting to apply specific designation to all sighted birds. Of the 125 specimens, 112 were Leach's and 13 were Galapagos Storm Petrels. No Harcourt's Storm Petrels were collected and I am uncertain as to whether this species was even seen although I tentatively identified at least eight sightings as belonging to this species. The great variation in size throughout the Leach sample indicates that at least two, and possibly more than two races are represented. Exceeding- ly small birds were taken which weigh less than many of the tiny Galapagos and exhibit most characters of this latter species (for a classical exam- ple, see specimen Field Series # 105225). Such individuals would be im- possible to distinguish from typical Galapagos in the field. On certain * This method avoids the need of heavy, cumbersome field glasses. A light- weight shotgun and plenty of ammo suffice.