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THE AMERICAN NATURALIST [Vol. XLVII 



pacifica have never been taken from the same region, 

 excepting in the case of the Siboga expedition when they 

 were obtained together in only one haul from 1,000 

 fathoms to the surface. 



Vertical Distribution of the Ch^tognatha of the 

 San Diego Eegion 



The 68,962 specimens of Chaetognatha obtained from 

 the San Diego region were distributed among the various 

 species as follows: 



8. bipunctata 51,670 



8. enflata 10,127 



S. serratodentata 6,575 



8. lyra 271 



8. neglecta 127 



E. hamata 72 



K. subtilis 50 



S. planUonis 41 



8. hexaptera 28 



P. draco 1 



Turning attention first to those species that must be 

 regarded as visitants rather than residents of this region 

 we find that S. enflata, S. neglecta, and the single 

 specimen of P. draco were all obtained from the upper 

 epiplankton mainly during February, 1905, when the sur- 

 face temperature was 15°. 5 C. One surface haul made on 

 the morning of February 25- obtained 3,500 S. enfata, 

 many of which were sexually mature, 9 immature 8. 

 neglecta, and the single very immature specimen of P. 

 draco. A second surface haul, made the same morning, 

 contained 3,100 S. enflata (most of them sexually mature) 

 and 75 immature S. neglecta. Six more S. enflata and 38 

 immature S. neglecta were obtained in a surface haul 

 made on April 29, 1905, and a seventh S. enflata in a sur- 

 face haul made on June 11, 1908. Of the remaining S. 

 enflata, 3,507 were obtained in open vertical hauls (from 

 ten fathoms or less) during the fall of 1904, 3,500 having 

 been taken in one haul. The five remaining S. neglecta 

 were also obtained in the same haul, and the 13 S. enflata, 



