140 University of California Publications in Zoology [Vol. 13 



altogether to prevalence of unfavorable temperatures. While the 

 relative number of hauls for those hours is smaller than for any other 

 time, it does not seem very likely that more hauls would lead to greater 

 success in collecting. If hauls are made between 4 and 8 a.m. and at 

 temperatures ranging from 14 ?1 to 17°, fairly large numbers of 

 animals are obtained and a few less than half the hauls are successful. 



The relation between salinity and other factors as affecting surface 

 distribution cannot be determined because the salinity is known for 

 but one of the surface hauls that obtained Nyctiphanes during the 

 winter. 



Since Euphausia was obtained in only four surface hauls, in large 

 numbers, it seems hardly worth while to consider the relation between 

 the abundance of this animal and combinations of factors as was done 

 for Nyctiphanes in table 14. It may be worth while to state, however, 

 that at optimum salinities (33.66-33.70) during the summer, about 

 seven times as many Euphausias are obtained on the surface per hour 

 when the temperature ranges from 16?l-17°as at any temperatures 

 (of those indicated in table 6) above 17°. Since the above maximum 

 for Euphattsia is based upon one successful haul, there may be consid- 

 erable doubt as to whether it even deserves mention. 



The above consideration of the occurrence and distribution of 

 Euphausia and Nyctiphanes contains facts as they are derived from 

 our data. It has been shown that Euphausia is more abundant at the 

 surface during June and July, while Nyctiphanes appears in larger 

 numbers during November and December (table 4). Those winter 

 months are the more favorable for both species, so far as the collec- 

 tions with the Kofoid net are concerned (table 5, section A). The 

 hauls made with the Nansen nets show that Euphausia is more abund- 

 ant in March and April, Nyctiphanes in November and December, but 

 it should be noted that only eleven animals of the latter species were 

 obtained in all the vertical closing hauls (table 5, section II). 



The general statement that is justified as to seasonal distribution 

 of the two commoner schizopods is : The number of animals and the 

 number of successful hauls is considerably larger during the colder 

 months (November to. April). 



Although Euphausia was more abundant during the summer, and 

 Nyctiphanes during the winter, the optimum surface temperature for 

 both lies between 16?1 and 17° (tables 7 and 8). 



Euphausia was not taken at the surface by day during the summer 

 (table 9), and the number of animals per hour at night is largest 



