TUNICATA 



229 



A special report on the pelagic Tunicata is being undertaken by Professor W. Garstang. 

 The species is patchy in its distribution, as is shown by the series of consecutive net 

 hauls described on p. 256 and illustrated in Fig. 135. It will be seen that the patches are 

 considerably larger than those of the Euphausians. This patchiness must be taken into 

 account when considering the distribution as revealed by our stations ; one station may 

 have been taken in a patch, another between two patches. Again, the species appears 

 to exhibit a marked vertical migration towards the upper layers at night, and this also 

 must be kept in mind and the chart of distribution in Fig. 98 compared with the chart 

 of night stations in Fig. 89. This vertical migration is further discussed and illustrated 

 on pp. 240 and 151. In spite of these difficulties there can be little doubt that the species 

 is present in larger numbers over the deeper water beyond the edge of the continental 

 shelf. An association between this species and the amphipod Vibilia antarctica is 

 described on p. 199. 



It was present in much greater numbers early in the season in November, December 

 and January than in March and May. 



Its depth distribution as shown by the N 70 V nets is given in the following table : 

 the figures have not been divided into night and day hauls because the distribution is so 

 patchy that it gives misleading results. 



Table XXXVII 



The depth distribution of Salpa fusiformis as shown by the N 70 V nets 



* Omitting two exceptionally high catches of 158 and 151. 

 f Omitting one exceptionally high catch of 103. 



Salpa fusiformis has been taken in Antarctic waters by the Belgica, 1 Southern Cross, - 

 National Antarctic (Discovery) 3 and Gauss 4 Expeditions. 



Oikopleura spp. The Larvacea were represented by specimens of Oikopleura which 

 have not yet been identified ; they will form the subject of a separate report being under- 

 taken by Professor W. Garstang. They were widely distributed in the area but rarely 

 abundant, occurring most frequently in November 1926, and May 1927, off the north- 

 east coast of South Georgia and at the oceanic stations between South Georgia and the 

 Falkland Islands in February 1927. 



1 Van Beneden (1913). 2 Herdman (1902). 3 Herdman (1910). 4 Apstein (1906). 



