26o DISCOVERY REPORTS 



discrepancy. Two well-known cosmopolitan species, however, were found to be distributed here rather 

 differently from what might have been expected from their previously known dispositions elsewhere. 

 C. lorenzianum, usually regarded as a neritic form, here reached its greatest relative importance in the 

 offshore samples, with a strong spring maximum. Conversely C. decipiens, one of the most widespread 

 of all oceanic species, was more plentiful here inshore in spring than it had been offshore during the 

 autumn survey. 



Table 25. Relative importance of the group Chaetoceraceae, and percentage of the several species ivithin 

 the group. Results arrayed according to distance from the land as shown, omitting those from the Orange 

 river line 



This evidence of a more panthalassic trend than was hitherto suspected for these two species, in a 

 region of exceptionally steep temperature gradients and rapid changes in conditions of the milieu, is 

 not surprising. Indeed, the general conformity of the majority of the genus to the distributional 

 pattern that might have been predicted from their known proclivities elsewhere, seems even more 

 remarkable to me under these conditions, which seem quite sufficient to account for the occurence of 

 both warm-water and cold-water forms together within a limited area. When the need for a reasonable 



