8 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 19 



The latitudinal and longitudinal lines used to mark off this area 

 result in 267 intersecting points (see Chart 1), from which the samples 

 originate. The departures from the exact even minutes are due to opera- 

 tional or economic factors, beyond the control of the experiment. The 

 precise locations are expressed in the Station List, below. 



The numbers, 2107-52 to 2859-54, are a continuation of the series 

 published earlier in the Allan Hancock Pacific Expeditions (vol. I, no. 3, 

 1943). Only stations in the San Pedro Basin for which quantitative grabs 

 have been taken, are here included. 



Temperatures were taken during the first year of the survey, by 

 immersing a centigrade thermometer in the mud sample just after it had 

 reached the deck of the ship. It was found that the readings were unreli- 

 able, since those from great depths were too high, due perhaps to the 

 effects of warming on ascent through the upper warmer layers of water. 

 The samples from shallow depths were frequently very small, making 

 the process difficult. On the whole it can be stated that the temperatures 

 of the shallower shelf vary diurnally and seasonally. The deeper parts 

 of the basin may be nearly homothermal, depending on depth. 



Based on readings taken by immersing a thermometer in the mud 

 sample on the deck of the ship, temperatures from shallow depths were 

 about as follows: 



Station 2124-52, no. 61. June, in 29 fathoms— 15.5° C. 

 Station 2152-52, no. 224d, Sept., in 19 fathoms— 14.0° C. 

 Station 2176-52, no. 164a, October, in 28 fathoms— 13.0° C. 

 Station 2217-52, no. 45b, February, in 12 fathoms— 11.5° C. 



Temperatures for greater depths, taken with a reversing thermometer 

 lowered to the water mass just above the surface of the mud, have been 

 made available by Dr. K. O. Emery, from transects taken from San Pedro 

 shelf to Catalina Island ; these are as follows : 



650feet (lOSfms)- 8.5°C. 

 1000 feet (167 fms)— 8.0° C. 

 1200 feet (200 fms)— 7.5°C. 

 1600 feet (267 fms)— 6.5° C. 

 1800 feet (300 fms)— 6.0° C. 

 2100 feet (350 fms)— 5.5°C. 

 2700 to 2850 feet (450 to 480 fms)— 5.04°C to 5.07°C. 



