218 I'liivcrsitij of California ['ublications in Zoologij [Vol. 15 



samples in the vicinity of the Gulf of California, 109° W. Although 

 those observations made within the gulf itself are not referred to by 

 sections but by the letter G, those outside and in the vicinity of the 

 Gulf require another form of reference, whence the use of negative 

 numbers. 



Any section cut by the coast line is designated in one of three ways : 

 when its center is within 2'5 west (or east) of the coast, the number 

 is bracketed; when it is within 2'5 north or south, the subscript or 

 exponent, as the case may be, is bracketed; when it is within 2f5 both 

 east or west and north or south, the entire symbol is bracketed. For 

 example, (40) j„ refers to a section whose center is within 2'5 west of 

 the coast, 55, „4, to one whose center is within 2'5 south of the coast, 

 and (39n,) to one whose center is within 2'5 north and west of the 

 coast. A more detailed discu.ssion of "sections" is given on pages 46 

 to 48 of our former (1915) report, and three maps are published by 

 McEwen (1916) which show the approximate number of observations 

 made from 1901 to 1915 in each section between Point Conception and 

 Cerros Island. 



EXPLANATION OF TABLE 1 

 This table includes the data relative to all the hydrographic obser- 

 vations made in the ocean from 1918 to 1915, inclusive, except those 

 made off Coronado Pier in connection with special observations in San 

 Diego Bay. 



First coJumii. — \\ater-s;iin|ilp numbers filtered in chronological order. 



Second cohimii. — Time when the sample was obtained, entered to the nearest 

 minute. 



Third column. — Section; for explanation see page 217. The letter G indicates 

 that the sample was taken in the Gulf of California. 



Fourth and fifth columns. — Latitude and longitude entered to the nearest OU 

 when the error was within 0;.5, and to the nearest minute when the error was 

 larger; for method of tabulating see page 217; for discussion of errors see 

 pages 18 to 21 of our former (191.5) report. 



Sixth column. — Depth of sample, entered to the nearest meter above and to 

 the nearest five below 200 meters; for discussion of errors see page 20 of our 

 former (1915) report. 



Seventh column. — Temperature in situ; all surface temperatures were deter- 

 mined by a thermometer (L. Steger, Kiel) reading directly to 0?2 C, and the 

 values entered may be regarded as accurate to 0?05 C. Subsurface temperatures 

 were determined by either Eichter or Negretti-Zambra reversing thermometers 

 (Helland-Hansen, 1911-1912, pp. 58-62), and the values entered are accurate 

 to within 0?01-0?05 C. Omitted entries indicate either that no temperature 



