RHIZOSOLENIA CURVATA 



429 



positions of the stations it was found impossible to include all our observations in 8o° W 

 longitude, for they lie too close together to be shown on a chart of manageable scale. 

 The repeated series have, therefore, been treated separately in Fig. 5, though one of them 

 (Sts. 985-991) is shown on the general distribution chart (Fig. 4) in order to facilitate 

 comparison with the results obtained elsewhere. Particulars of all the other positive 

 records shown in Fig. 4 will be found in Table V. The observations in longitude 8o° W 

 are treated separately in Table VI. 



▲ Valdivia records 

 • Positive records 

 O Negative records 



Fig. 3. Observations of Rhisosolenia curvata in the Southern Indian Ocean and south of Australia. 



The majority of the records south of the Tasman Sea and in the western portion of 

 the Southern Pacific Ocean show few exceptions to the general theory of the distribution 

 of R. curvata developed in other areas. In general the richer catches were obtained at 

 sub-Antarctic stations at fairly high temperatures for the species, while at the one 

 exceptionally warm station (922) the species was rare. All the records of the species on 

 the Antarctic side of the convergence lie within the probable limit of occasional mixing. 

 Mr Clowes informs me that between Sts. 1274 and 1276, which were worked in summer 

 when southward mixing is less likely to occur, the convergence was unusually ill-defined. 



When we come to examine the records from the eastern portion of the Southern 

 Pacific Ocean, we find that while the species showed a normal distribution on the series 

 of observations in longitude 8o° W, it was present in considerable numbers at a small 

 group of stations lying between 90 and 220 miles south of the probable average position 

 of the convergence farther to the westward. These stations are anomalous. Unfortunately 

 they represent the most northerly points reached during a fortnight's work, the bulk of 

 which was carried out much farther to the southward, beyond the range of the species, 

 so that it is only possible to put forward a tentative explanation. I believe it possible 



