160 University of CaJifornia Puhhcatlons in Zoology. [Vol. 8 



3. Sagitta enflata, S. neglecta, and Spadella draco cannot be 

 regarded as typical of the San Diego region. They were all 

 taken from above 10 fathoms, and are, therefore, strictly epi- 

 planktonic. 



4. Eukrohnia Jiamata is typically mesoplanktonic. It has, 

 however, been taken above 100 but not above 25 fathoms. 



5. E. subfilis was not taken above 50 and only rarely above 

 150 fathoms. The species is, therefore, mesoplanktonic and its 

 center of migration is probably between 200 and 250 fathoms. 



6. Comparison of the distribution of all the species shows 

 conclusively that manner of distribution is correlated with the 

 organization of the species. In other words, the distinctive man- 

 ner in which each species is distributed is as much a specific 

 character as is its structure. 



Such evidence as was obtained, especially concerning S. 

 bipunctata, can not be regarded as proving the conclusions ad- 

 vanced in this paper. To prove would require much more 

 collecting with respect to light, temperature, salinity, gas con- 

 tent, season, location, and other factors. It would further 

 require special apparatus for determining the amount of light 

 throughout day and night in the various depths, and the number, 

 direction, velocity, and alterations of currents in all depths. It 

 would also require determination of net coefficients, or better, 

 the use of nets of similar size, mesh, and filtering capacities in 

 collecting in all depths. To call attention to this necessity for 

 improved and more complete methods in collecting is one of the 

 greatest values of this paper. However, in spite of the less 

 adequate methods employed, the data strongly support the 

 conclusions made. 



Marine Biological Laboratory, La Jolla, Calif. 

 Transmitted February 11, 1911. 



