276 University of California Puhlicatiois in ZooJogi/ [Vol. is 



Table 11 



Surface distribution of Salpa democratica during June and July, 



1908 and 1909, relative to three temperature groups 



Solitary forms Aggregate forms 



> r 



Specimens Frequency Specimens Frequeno 



7.9 5,750 640 88 97 

 20.5 6,014 193 66 77 

 19?l-20?6 18 14.3- 11.4 4,011 280 80 87 11.0 3,111 218 77 84 



Each of the four conditions deduced from the locomotion theory 

 is shown by this table : 



1. The frequencies of the two generations are identical relative 

 to the lowest temperature group, nearly so relative to the highest, 

 and parallel throughout. The frequency of both is lowest in water 

 of medium temperature (17?5C-19?0C). 



2. The frequencies of both generations are greater in the coldest 

 than in the warmest water. 



3. Abundance of aggregate forms parallels frequency of both gen- 

 erations, being highest (640 per hour) in the coldest water, and 

 lowest (193 per hour) in the water of medium temperature. 



4. Abundance of solitary forms increases from 52 per hour in the 

 coldest water to 73 per hour in water of medium temperature to 280 

 per hour in the warmest water. 



In table 12 the data are retabulated again in four groups according 

 to whether the temperature lay between 15?9C and 17?1C, 17?2C and 

 18?3C, 18?4C and 19?5C, or 19?6C and 20?8C. Be it noted that the 

 two middle groups each have a range of 1?2 C, while the two extreme 

 groups each have a range of 1?3C. 



Table 12 



Surface distribution of Salpa democratica during June and July, 1908 

 and 1909, relative to four temperature groups 



Solitary forms Aggregate forms 



Specimens Frequency Specimens Frequency 



