LISTS OF SPECIES BY STATIONS 



63 



Volume of tow, 36 cm'; length, 2.9 miles; time, ll''!?"' p.m. 

 to 12''30"' A.M. This third surface tow was taken with the same 

 net later during the same night, but in the interval the ship 

 had moved several miles from its former position. This tow 

 contains 16 species that do not appear in the two former tows 

 and it fails to show 14 species that were found there. In the 

 three tows, therefore, 40 of the 58 species (70 per cent) appear 



in a single tow only, and many of the remaining 30 per cent 

 show marked differences in their relative abundance. Val- 

 diviella minor here appears at the surface in the night, whereas 

 the other two records are in the 100-meter tow at station 50 

 and the 1000-meter tow at station 64. This species, then, is 

 another that migrates to the surface in the night, but stays 

 below 100 meters most of the time during the day. 



Station 51 

 December 1, 1928; 29° 06' S, 114° 48' W; bottom depth, 2898 m; 50 species 



Depth of tow, m 

 Temperature, °C 

 Salinity, 0/00 

 X'olume of tow, cm' 



Acrocalanus gracilis c 



Calocalanus pavo 



Candacia bispinosa 



simplex 



Centropages calaninus f 



Clausocalanus arcuicornis f 



Clytemnestra scutellata 



Copilia denticulata 



quadrata 



Corycaeus agilis 



catus a 



crassiusculus 



lautus r 



limbatus 



typicus 



Farranula carinata c 



concinna f 



carta 2 



gibbula a 



gracilis c 



rostrata 



Haloptilus acutifrons 



longicornis 



Heterorhabdus spinifrons 



Labidocera detruncata f 



Lucicutia clausii 



Macrosetella gracilis. . . . 



Mecynocera clausi 



Metridia brevicauda. . . . 

 Microcalanus pygmaeus. 



Microsetella rosea 



Neocalanus gracilis 



robustior 



tenuicornis 



Oithona attenuata 



plumifera 



similis 



spinirostris 



Oithonina nana 



Oncaea media 



minuta 



similis 



Paracalanus parvus 



Pleuromamma gracilis. . 



Pontella tenuiremis 



Pontellina plumata 



Pseudocalanus minutus. 

 Sapphirina auronitens. . 

 Undinula caroli 



darwinii 



The temperature differed less than 3° in the 100 meters, 

 and the salinity and hydrogen-ion concentration showed no 

 variation. Fifteen species were found at the surface, only 5 

 in the 50-meter tow, and 42 in the 100-meter tow. Thirty-nine 

 species (78 per cent) were each confined to a single tow and 



only 1, Pseudocalanus minutus, was present in all three tows- 

 In the small number of copepods, only 8 in all, that are 

 recorded for the 50-meter net, this list differs radically from 

 all the others. Something must have happened to this tow 

 which does not appear anywhere in the records. 



