102 TJniversity of California Publications in Zoology. [Vol. 8 



same evening, one from 6 :00 to 6 :45 p.m., the other from 7 :30 

 to 8 :00 p.m., which did not contain a single Chaetognath, and 

 that the temperature of the water was 18?4 C. during all four 

 hauls. 



4. On June 21, 1909, two surface hauls, 1680 and 1682, were 

 made with the same net, the former at 32° 52:0 N and 117° 32:9 

 W, and the latter 0:1 farther north and 0:2 farther west. Haul 

 1680 began at 7 :00 p.m., haul 1682 at 7 :40 p.m., and each lasted 

 35 minutes. The former contained 3600 and the latter 80 speci- 

 mens of 8. hipwictata. Thus, within one hour the number of 

 specimens varied from 45 to 1 per unit volume of water. 



5. On June 28, 1909, four surface hauls, 1744, 1747, 1751, and 

 1754, were made with the same net at 32° 52:0 N and 117° 30:0 W. 

 Haul 1744 lasted from 5 :00 to 5 :20 p.m., haul 1747 from 6 :35 

 to 7 :11 p.m., haul 1751 from 7 :15 to 8 :00 p.m., and haul 1754 

 from 8 :10 to 8 :50 p.m. The first haul contained 2 specimens 

 of 8. hipunctata, the second contained none, the third contained 

 155, and the fourth contained 1100. The temperature of the 

 water was 19 ?2 during haul 1744, and the salinity was 33.648 

 During the other three hauls the temperature was 19.2° and the 

 salinity was 33.603. The number of specimens per unit volume 

 of water bear the proportion of 1 to to 128 to 1100. 



6. On July 9, 1909, three surface hauls, 1850, 1854, and 1860, 

 were made with the same net at 32° 52:3 N and 117° 20:0 W. 

 The temperature of the water was 18? 8 C. during the first two 

 hauls and 18?62 during the third. The salinity was 33.690 

 during haul 1850, 33.570 during haul 1854, and 33.589 during 

 haul 1860. Haul 1850 lasted from 3 :30 to 4 :15 a.m., haul 1854 

 from 4 :20 to 5 :15 a.m., and haul 1860 from 5 :18 to 6 :25 a.m. 

 The first contained 270 specimens of 8. hipunctata, the second 

 contained 6, and the third contained 4. From 3 :30 to 6 :25 a.m. 

 the number of specimens per unit volume of water varied from 

 135 to 1. 



7. This example illustrates the rapid rate with which some 

 physical conditions of the water may change. Surface haul 

 1868, made on July 9, 1909, from 7 :03 to 7 :36 p.m. at 32° 52:3 N 

 and 117° 20:0 W, contained 10 specimens of 8. hipunctata. A 



