At the mouth of the Gulf of California no oceanographic data were collected. However, as the Gulf was approached from the southeast a distinct current line was crossed. This suggests that the vessel was entering a different water-type, which is a logical presumption in light of the known oceanography. Off Cape San Lucas another water type was probably present, but no signs of a division were observed by the writer beyond slim suggestion by bird distribution. The last major area of water being considered is that in the southern extremes of the survey area south of the North Equatorial Countercurrent. The water was characterized by high salinities and low temperatures and was probably the northern portion of the westward flowing South Equatorial Current. One other portion of the survey area will be considered as another water type although insufficient oceanographic data were collected to justify such a separation. However, on the basis of bird distribution such a division seems reasonable. Thus the section of the western leg of the cruise between 15° and 28°N will be treated as a separate water type. As mentioned above, the oceanographic characters of a water type are either directly or indirectly major factors in delineating species and density distribution of birds. Whether this holds true for migrants as well as resident birds will not be a concern in this report as there was little suggestion of migratory travel throughout the cruise. Thus it is felt that a correlation of distributions and water types would reflect the uninfluenced effect that water types have on the presumed resident birds. The divisions as established in the above discussions are shown in map 2; maps 3 and 4 show surface temperatures and salinities for additional reference, and table 2 shows the species breakdown for each area. Table 3 shows species habitat (water type) preference in a simplified form. SPECIES ACCOUNTS (Note: Only species for which there is additional information are listed below. See Tables for total avifauna.) Procellaria sp. A single bird which was probably a Black Petrel (Procellaria parkinsoni) "...bird all dark, light-colored bill (which was fairly short); body shape much like an albatross, wings shaped like an albatross. Flight was very distinctive,...frequent twisting and turning, a rapid flight; smaller than a Black-footed Albatross, but (slightly) larger than a Pink-footed Shearwater; tail was quite short." An accompanying drawing of the underwing shows that it was all dark with a lighter area on the ventral tip.