ter, Washington, D.C.]. The temperature distributions at 0, 10, 25, 50 and 

 75 m at the time of the surveys are illustrated in Figures 2-47. The loca- 

 tions of stations occupied during each of the 10 surveys are indicated on the 

 surface temperature charts by dots. Figure 1 illustrates the bathymetry of 

 the region, and Figure 48 shows the deviations of mean monthly temperatures 

 at Naos Island, Canal Zone, from the long-term monthly mean. Data for the 

 last figure were taken from Coast and Geodetic Survey Publication 31-3 (1962). 



COMMENTS ON, AND INTERPRETATION OF, THE FIGURES 

 Bathymetry. Figure 1 



The Gulf of Panama is a shoal area less than 200 m deep. The Las Perlas 

 Islands lie within the Gulf, east of its center. To the west of these islands 

 the bottom contours penetrate farthest northward, so that the thalweg lies in 

 a shallow trough directed toward the head of the Bay of Panama. 

 Survey #1, 20-22 March 1955. Figures 2-6 



The waters ranged in temperature from 21° to 26°C at the surface, and be- 

 low 25 m temperatures were between 14° and 19°C. The strongest northerly wind; 

 for the year were recorded during this month and sea level was lowest. The 

 surface temperature was the lowest over a greater portion of the Gulf of Pana- 

 ma during this period than during any other observational period considered 

 here. This cold pattern coincides with the observations of Bennett (1963) who 

 noted that 1955 was an exceptionally cold period in the Eastern Tropical Pac- 

 ific. The greater cold anomaly is also noticeable in Figure 48. 



The isotherm pattern is consistent with strong upwelling at the head of 

 the Gulf (Bay of Panama) and perhaps off San Miguel Say. The latter location 

 is noted tentatively because of the lack of other upwelling indices and the 

 possibility that the low temperatures recorded off that bay may simply be the 

 result of an influx of cooler river water into the Gulf. At depths of 50 and 

 75 m, maximum penetration of cool water is on the west side of the Gulf, along 



