Ecuador) northward to about 23°N, at the 

 mouth of the Gulf of California. Seasonal 

 countercurrent development sometimes leads 

 to a slight transgression of these limits but 

 the range is, in any case, latitudinally 

 asymmetrical, like that of many other marine 

 organisms inhabiting the warm zone between the 

 Peru and California currents. 



such as off the semiarid Pacific coast of 

 Mexico, turtles may offer birds the commonest 

 and most used resting "islets". We repeatedly 

 saw boobies of two species, as well as certain 

 other birds, perched upon their backs. 

 Evidently such stowaways do not incommode the 

 surfaced turtles. This matter is referred to 

 further in the account of the birds. 



Chelonia. Sea turtles. Turtles sighted 

 during the cruise of Stranger probably 

 included four species, namely Chelonia mydas 

 (green) Eretmochelys imbricata (hawksbill), 

 Caretta caretta (loggerhead), and 

 Lepidochelys olivacea (Pacific Ridley) . The 

 last two, both of loggerhead type, were 

 undoubtedly the commonest, and the only turtle 

 captured and certainly identified was 

 Lepidochelys . Identification of turtles in 

 the water at various distances offers 

 difficulties because of the changes in the 

 margin of the carapace that take place with 

 age and growth. 



The example of Lepidochelys olivacea was 

 taken on Nov. 23 at 09°^1' N, 89°Mt-' W, 

 about 220 miles from the nearest land. Its 

 carapace was 51 cm. in length. On the left 

 side of its snout it bore a large barnacle, 

 not yet identified. 



All other examples seen from shipboard had 

 best be listed merely as "turtles" . They 

 were noted as especially abundant on seven 

 different days of the cruise, namely 

 Nov. 13, ll+, 16, 23, 25, and Dec. 1 and lk. 

 Turtles were seen also on many additional 

 days in both coastal and (ff shore areas 

 between latitudes 26° N and Ok" N. The total 

 range of surface temperatures throughout 

 these waters and dates was 2^.8° to 29.7°C. 



Sea turtles, like many oceanic fishes, show 

 great interest in flotsam. I repeatedly saw 

 them change course to approach the skiff or 

 one of the ship's floating bamboos supporting 

 a radar reflector . They would then nudge or 

 rub against the hard objects for long periods. 



My most interesting observations concern the 

 ecological importance of turtles as resting 

 places for sea fowl. In seas of sparse flotsam, 



BIRDS 



Gavia immer. Loon. One seen Dec. 16 off the 

 coast of Baja California near the United States 

 border . 



Fulmarus glacialis rodgersi . Pacific fulmar. 

 A gray-phase female collected Dec. 12 at 

 23°31' N, 111 8 22' W. This is 30 miles offshore, 

 halfway between Santa Margarita Island and 

 Cape San Lucas (surface water 2^°C) . The 

 specimen probably represents the southernmost 

 record of the fulmar in any ocean. 



Puffinus creatopus . Pink-footed shearwater. 

 Observed, always singly, on six days during 

 the cruise between the coastal waters of 

 southern Baja California and the vicinity of 

 Cocos Island. A casual representation of this 

 southern-hemisphere breeder north of the equator 

 during the normal nesting season is to be 

 expected. 



Puffinus griseus . Sooty shearwater. A case 

 akin to that of the preceding species. Single 

 birds twice noted, once on Nov. 13, off 

 southern Mexico (surface water 29.7°C), and 

 again on Dec. 13, off Cape San Lazaro, Baja 

 California. 



The sooty shearwater nests in the antiboreal 

 zone and usually passes rapidly across the 

 tropics on its migrations between higher 

 latitudes of the opposite hemisphere. 



Puffinus gavia opisthomelas . Black- vented 

 shearwater. Many seen feeding, in company with 

 other petrels and terns, about kO miles off 

 Punta San Telmo, SE of Manzanillo, Mexico, 

 Nov. 13. The birds were in a natural oily 

 "slick" on the ocean. 



On the return voyage, when we were bound north- 



- 103 



