268 Unwersity of California PiihlicaHons in Zoology IToi" IS 



these sections, and this table as well as table 4 reveals the differentials. 

 Again the excess of cold water hauls in section 46^o can not have been 

 responsible, for none of the hauls involved, in table 5 were made in 

 this section. Finally, the excess of warm water hauls in section 52io 

 can not have caused the differentials, because none of the hauls 

 involved in table 6D were made in this section. 



All the sections except 42^0 and 43^0 are thus eliminated from 

 further consideration. Relative to the latter, all the hauls were made 

 in the colder water. According to the hypothesis in question this 

 might account for the excess of aggregate forms in the colder water. 

 Still, it obviously can not account for the excess of solitary forms in 

 the warmer water. But, neither can the distribution of hauls in sec- 

 tion 42io account for it, for not only were more cold than warm water 

 hauls made in this section, but table 9 shows that none of the warm 

 water hauls involved in table 6B were made in it. Furthermore, every 

 haul made in this section was made within 0'3 of 32° 52'N and all 

 except one (1657), which failed to catch a single individual of either 

 generation, within 0?4 of 117? 30'W. Finally, every haul save one 

 (1815, made on July 7, 1909) was made between June 15 and June 29, 

 1909. This obviously means that, even if stratified areas of warm and 

 cold water did exist within the required limits of approximately 0.64 

 square miles — a highly improbable occurrence — the time elapsed was 

 insufficient to enable the excess of solitary forms and deficiency of 

 aggregate forms in the warmer water to have arisen in consequence 

 of an increased production of the former and death of the latter. It 

 follows, then, that if table 4 be reconstructed by eliminating all hauls 

 except those made in section 42io, this stratification hypothesis will 

 be put to its final test. Table 10 shows the result? of such reconstruc- 

 tion. 



Table 10 



Eeconstruction of table 4 by eliminating all hauls except those 

 made in section 42^0 



Solitary' forms Aggregate forms 



Specimens Frequency Specimens Frequency 



10.7 726 68 100 100 10.7 3,306 309 100 100 

 5.3 1,354 229 90 98 4.0 942 160 68 80 



