Sea surface temperatures have been taken daily at Keppel Pier, Millport (55° 44‘ 55“ N. lat.; 4° 54’ 20” W. long.), for the past 10 years (1949–58), the data being included in returns to the Meteorological Office. The records are not given in their standard publication and they are, therefore, presented here to supplement those of Cooper (1958) for inshore waters at Plymouth some 400 miles farther to the south. For some years the samples were drawn in a specially constructed container fitted with a Fahrenheit thermometer which was read to the nearest whole degree; more recently the bucket method has been used, and a centigrade thermometer graduated in degrees and read to an estimated tenth of a degree. The two methods were checked against each other before the change was made and the results found to be consistent. All readings were taken at 09.00 h G.M.T., irrespective of the state of the tide. The results are shown in Table 1.