collection. These establish the race as that 

 breeding at the Galapagos Archipelago. A 

 slightly smaller form nests on islets along 

 the coast of Peru. 



Two males at the peak of breeding condition 

 were taken on Nov. 10 at 22°57' N, 113 , 3^' V, 

 a few miles N of the isolated Alijos Rocks 

 and nearly 200 miles W of Cape San Lazaro, 

 Baja California. Thereafter the species was 

 encountered all along our course to the "Dome" 

 area, Nov. 19-23. We met it again outside 

 the Gulf of Panama, in the waters around 

 Cocos Island, and for a thousand miles toward 

 the NW until Dec. 8. The range of surface 

 temperatures throughout these areas and dates 

 was 2l*.l° to 29.6°C. 



Oceanodroma leucorhoa . Leach's petrel. Two 

 specimens collected, but which of the four 

 subspecies currently recognized along the 

 Pacific coast of North America they represent 

 has not yet been determined. It is likely 

 that the typical and most northerly race 

 migrates farther southward than any of the 

 other three. 



The pattern of distribution of Leach's 

 petrel during the cruise of Stranger closely 

 matched that of the preceding species. The 

 first specimen flew aboard S of the Alijos 

 Rocks during the night of Nov. 9. Thereafter 

 the species was logged on Nov. 10, 11, 19, 20, 

 21-23, to the "Dome" area. Later, Dec. 2-1*, 

 we found it at 0V09' N, 83*31+' W, in waters 

 around Cocos Island, and for about 200 miles 

 northwe stwar d . 



Probably surface temperatures have little 

 significance in relation to the winter 

 distribution of this storm petrel. 



Loomelania melania. Black petrel. This 

 species nests at Los Coronados and San 

 Benitos islands W of Baja California and at 

 islands of corresponding latitudes within 

 the Gulf of California. It migrates south- 

 ward to the ocean off northern Peru, but 

 avoids the cool waters of the Peru Current . 

 Its winter range S of the equator appears to 

 be determined, indeed, by surface temperatures 

 dependent upon current-countercurrent controls , 



The black petrel was logged very frequently 

 between Nov. 11, at 21 c 07' N, 109*56 ' W 

 (S of the Alijos Rocks) to western Panama 

 and the Gulf of Panama. Later we found it at 

 our southernmost station (0V09' N, 83*31*' W), 

 around Cocos Island, and N toward the continent 

 to the latitude of Cape San Lazaro on Dec. 13. 

 The amplitude of surface temperature among all 

 the observations was about 2l*°C to 29.6°C. 



Five specimens were collected. They had heavy 

 deposits of subcutaneous fat, as befits birds 

 in the early stages of a long migration. In 

 fact, they were the fattest of the four species 

 of storm petrels obtained on the expedition. 



A female shot on Nov. 14, at l6°l6' N, 

 100*27' W, had her stomach and gullet crammed 

 with lantern fishes of a uniform 1*0 -mm. length. 



Of all Pacific storm petrels of my personal 

 acquaintance, this one is most persistently 

 given to following vessels. The birds 

 accompanied Stranger for days on end, sweeping 

 widely across the wake and apparently 

 profiting from the artificial turbulence of 

 the water rather than from food cast overboard. 



Halocyptena microsoma. Least petrel. Like the 

 preceding species, this tiniest of petrels 

 nests in the Mexican Pacific and Gulf area and 

 migrates southward into equatorial waters. 



It was observed and occasionally collected along 

 our course between Nov. ll+ and Dec. 16. There 

 were periods of days in which none was seen, 

 but these appeared to have nothing to do with 

 latitude or with distance from the continental 

 coast . The northernmost record was near Cape 

 San Lazaro, Baja California, Dec. ll*. Surface 

 temperatures on all days on which the species 

 was noted ranged from about 2V to 29.6°C. 



Phaethon aethereus . Red-billed tropic -bird; 

 boatswain-bird. Found in abundance at the 

 Alijos Rocks (21**57' N, 115*1*3' W), Nov. 9, 

 and casually observed in both coastal and 

 pelagic waters on eight other days, as far N 

 as Cedros Island, Baja California. 



Alijos Rocks, approximately 185 miles W of 

 Cape San Lazaro, seem to have been bypassed by 



105 



