64 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



the Gulf around 27°30'N. contained fewer than 1,000 cells per liter. 

 One catch of 50,375 cells was taken southeast of Las Animas Point 

 (28°49'N. latitude, 113°13'W. longitude), a catch of 27,951 cells 

 a little south of the San Lorenzo Islands, and one of 19,375 cells on 

 the east side of the Gulf in latitude 27°8'N., longitude 110°27'W. 

 All other catches contained fewer than 10,000 cells per liter and most 

 of them fewer than 1,000 cells. 



No other Expedition has gone so far north in the Gulf as did the 

 1937 one. In 1921 (April 26), two catches were taken on the eastern 

 side of the Gulf about ten miles southwest of Georges Bay. One of 

 these contained 4,428 cells, the other 196,621 {Chaetoceros species 

 66,976 cells, Leptocylindrus danicus 63,700 cells) showing that a large 

 production does occur in this region at times. North of San Luis Island, 

 near the western side of the Gulf just south of 30 °N. latitude, two 

 catches were made on April 28, one containing 207,284, the other 

 220,078 cells per liter. Again Chaetoceros species predominated. 



In 1921, as in 1937, the region around Angel de la Guardia Island 

 was highly productive. On that Expedition a number of catches were 

 taken near the southern end of the Island as well as to the north. In 

 the latter part of April, early May, and again toward the last of June 

 large catches were taken near the southern end or south of the Island. 

 The largest of these, estimated to contain 572,317 cells per liter, was 

 collected on June 25. Chaetoceros species, C. compressus, and C. radicans 

 were abundant. In the larger catches of April and May Thalassionema 

 nitzschioides was the leading species in number of cells. Toward the 

 north of the Island a catch of 592,720 cells (Chaetoceros debilis and 

 Thalassionema nitzschioides) was taken on May 1 and one of 118,152 

 cells ( Chaetoceros species and C. didymus) on June 29. Near the south- 

 eastern point of Tiburon Island two catches of over 100,000 cells per 

 liter were collected on July 4. This region would appear to be a pro- 

 ductive one in 1921 as well as in 1937 although the catches were taken 

 three months later in 1921. Chaetoceros species, C. curvisetus, and 

 Cerataulina bergonii were most numerous. The third region mentioned 

 as being highly productive in 1937 was represented by only two very 

 small catches taken on July 10 and 11 in 1921. 



In the 1936 series two catches, one of 205,296 cells per liter, the 

 other of 115,484 cells, were taken between Angel de la Guardia and 

 the coast of Lower California on March 2. Chaetoceros debilis, 

 Nitzschia seriata, and Chaetoceros curvisetus predominated. Three 



