22 University of California Fuhlicatlojis in Zoology [Vol. 13 



to note that the commonest ctenophore is found much less frequently 

 than the commonest chaetognath or copepod. For example, Sagitta hi- 

 punctata was obtained in 72 per cent of the surface hauls (Michael, 

 1911, p. 115), and Calanus finmarckicus was present in 57 per cent 

 of the hauls (Esterly, 1912, p. 281). If we consider that the surface 

 hauls are now distributed over parts of five different years, it is not 

 unreasonable to feel that the haul frequency for the Ctenophora would 

 not be changed materially if there were many more hauls available. 

 The difficulty as to irregularity in hauling is the same as that en- 

 countered in the studies of chaetognaths and copepods; but certain 

 general conclusions as to the behavior of those groups are justified, 

 and this is apparently true for Pleuro'brachia among the Ctenophora. 



Table 1, which follows, lists the successful surface hauls and the 

 numbers of animals. 



TABLE 1 

 A List of the Sucgessful Surface Hauls, and the Numbers of Animals 



Numbers of Specimens 



Beroe 



Haul No. 



Pleurobrachia 



Euplokamis 



1452 



1 





1499 



2.53 







1500 



181 





1568 



20 





1582 





1 



1650 



25 





1653 



150 





1655 



200 





1657 



72 



1 



1680 



16 



1 



1682 



8 



1 



1695 



1 



1 



1698 



1 



1 



1763 



13 





1784 





13 



1804 



1 







1836 



1 







1850 



3 



3 



1854 



5 





1875 





31 



1881 





16 



1910 





.... 



1915 



250 





1920 



■ 1 





2178 



1 





59 

 3 



