45 



never captured in the numerous hauls at the surface, but were captured with fair regularity in 

 the small number of deeper nets, they probably only lived at some considerable depth, and 

 that the horizon to which the net which caught them at the least depth was lowered, may 

 have approximately represented their upper limit of distribution. Of Zetesios and hamata on 

 the other hand, we may say positively that they occurred between 975 and 415 metres. 



In the case of three of these species, the table below shows in metres the least depth 

 observed, for comparison with inferences drawn from their distribution in the Biscayan report. 



Research 



Young, ?639; large, 731 — 914. 

 Young, 182; large, below 548. 

 Young, 91 ; large, below 914. 



The data yielded by open vertical nets used at considerable depths are too uncertain 

 to allow of any positive deduction, although the figures seem to point in a particular direction. 



Subtilis was probably here, as in the Bay of Biscay, a sub-surface form in the lower 

 epiplankton, but the zones of the first 100 fathoms were not so systematically explored by 

 the Siboga that this can be affirmed with certainty; the hauls, so far as they go, point in 

 this direction. 



Of the remaining species represented in the collection, it can only be said that they all 

 occurred at the surface, and were therefore epiplanktonic. Some of them may or may not have 

 penetrated into the mesoplankton, but the mere fact that they were captured in open vertical 

 .nets lowered to considerable depths, is no evidence of this. 





Siboga 



macrocephala 



I5OO 



Zetesios 



?75o 



hamata 



900 



b. COMPARISON WITH THE EPIPLANKTONIC FAUNA OF JAPAN AND OF THE MALDIVE ARCHIPELAGO. 



In view of the usually accepted statement of the uniformity of the epiplankton over the 

 Indo-pacific Ocean, it is worth while to compare the captures of Aida in Japan, of Doncaster 

 in the Maldive Archipelago, and of the Siboga Expedition. The comparison certainly strongly 

 points to such an uniformity. 



.. 'Valid' species. 



Misaki Harbour. 



Siboga area. 



Maldive Archipelago. 



Bedoti 



+ 



+ 



+ 



enflata 



+ 



+ 



"T 



ferox 





+ 



+ 



hexaptera 



H- 



+ 



+ 



minima 



+ 







neglecta 



+ 



+ 





pidclira 





+ 



+ 



regularis 



+ 



+ 



+ 



robnsta 





+ 



t 



serratodentata 



+ 



+ 



+ 



pacifica 



+ 



+ 



+ 



subtilis 





+ 





draco 



+ 



+ 



+ 



