LISTS OF SPECIES BY STATIONS 



73 



Station 60 

 December 26, 1928; 40° 24' S, 97° 33' \V; bottom depth, 4007 m; 12 species 



Depth of tow, m 

 Temperature, °C 

 Sahnity, o/oo 

 \ ohimc of tow, cm' 



Clausocalanus arcuicornis. 



furcatus 



Mecynocera clausi 



Microsetella rosea 



Oithona brevicornis 



similis 



Oncaea media 



Paracalanus parvus 



pygmaeus 



Pseudocalanus minutus. 



Scolecithrix danae 



Undinula darwinii 



This station was the farthest south for the entire cruise 

 and had a low surface temperature with a drop of 4° in the 

 upper 100 meters; the salinity and hydrogen-ion concen- 

 tration were moderate and constant. This is one of the lowest 

 totals of species for stations in the Pacific, with 5 species at 

 the surface, 9 in the 50-meter tow, and 9 in the 100-meter tow. 

 Four species only were each confined to a single tow and 3 

 were present in all three tows. The length of the surface tow 

 was only half that of the other two tows, but its volume was 



nearly twice as great. Though the ctenophores were con- 

 siderably reduced in number, they still made up the bulk of 

 the surface tow. Paracalanus and Pseudocalanus were excep- 

 tionally abundant at the surface, Mecynocera and Oithona 

 similis in the SO-meter tow, the latter in the 100-meter tow. 

 Corycaeus was absent from this station and the following one, 

 but reappeared between stations 61 and 62, and 5 species 

 were present at the latter station. The fortieth parallel is 

 probably a little too far south for this genus. 



Between st.\tions 60 and 61 



A. December 26, 1928, 4'> SO" to 5'' 50"- p.m.; 40° 26' S, 97° 12' W 



B. December 26, 1928, 7>' SO"- to lO"- 20°' p.m.; 40° 22' S, 97° 02' W 



C. December 26, 1928, 10'' 25"' p.m. to l"" a.m.; 40° 22' S, 96° 59' W 



16 species 



Location of tow 



\ olume of tow, cm' 



A 

 64 



B 



36 



Location of tow- 

 Length of tow, 



miles 



A 

 3.0 



C 



1.6 



Acrocalanus gracilis 



Calanus tonsus 



Clausocalanus arcuicornis. 



furcatus 



Microsetella rosea 



Neocalanus gracilis 



Oithona brevicornis 



similis 



Oncaea curvata 



similis 



Paracalanus parvus 



Pleuromamma gracilis . . 

 Pseudocalanus minutus. 



Scolecithri.x danae 



Undeuchacta major. . . . 

 Undinula darwinii 



These three surface tows were taken the same night but a 

 few miles apart. The first tow, from S"* to 6'' in the late after- 

 noon, yielded 7 species; the second tow, from S"" to 10'' in the 

 evening, yielded only 2 species; and the third tow, over mid- 

 night, yielded IS species. It is also worthy of note that the 

 third tow, although shorter than the second, yielded a volume 

 eight times as large, and this volume was four and a half times 

 that of the first tow, although the latter was twice as long. 

 That the midnight tow should contain twice as many species 

 as either of the others is, however, exactly what would 

 be expected as a result of nocturnal migration. The 

 species found in it that were not present in the other tows 



are the ones that require a longer time to reach the surface. 

 This may be due to slower progress or to a longer distance 

 traversed, Undeuchacta probably coming under the latter al- 

 ternative, and Oncaea perhaps representing the former. Clauso- 

 calanus and Oithona comprised 99 per cent of the first tow, 

 the second tow was e\-enly di\-ided between Oithona and Cala- 

 nus, and no single species of the third tow stood out with any 

 prominence. Nine of the species (56 per cent) were each con- 

 fined to one of the tows, and only a single species was present 

 in all three tows. These three tows thus present considerable 

 diversity in the surface distribution of the copepods, appar- 

 ently due to the time of day at which the hauls were made. 



