184 DE. G. H. FOWLEE— BISCATAN PLANKTON: 



traversed drop to about 01 in the Bay of Biscay. If so, it is all the more curious, 

 since digitalis failed at temperatures above 46° in the Faeroe Channel, and the supposed 

 digitalis above 46°-49° in the Bay of Biscay. While fully recognizing that these may 

 be only double coincidences, I incline to the idea that they really give us the approxi- 

 mate temiierature-limits of these two species — the maximum for digitalis, a truly Arctic 

 form described from Greenland ; the minimum for rosea, a temperate and tropical form. 

 Unfortunately, owing to Haeckel having united them, it is practically impossible to be 

 certain to which of them the older records refer ; otherwise we should have a reliable 

 check on this question. But it is Avorth noting that in a collection of Medusae from 

 Norway and Spitzbergen, on which Mr. Browne reported for the Bergen Museum 

 (References, p. 181 above, Browne, 1903), Aglantlia rosea extended from Southern 

 Norway up to just inside the Arctic Circle (Skjerstadfjord), while Aglantha digitalis 

 appeared only from the Lofoten Islands. This fits in weU with the previous suggestion, 

 and points to the probability that^. rosea prefers warmer water than digitalis ; although 

 they may overlap at about their temperature-limits, the maximum of the one is probably 

 fairly close to the minimum of the other, and neither is very far from 47° E. (8°3 C). 



* 



Aglauka HEMiSTOMA, Peron & Lesueur. 



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Several of the epiplanktonic species treated earlier in these Reports have shown a 

 marked and puzzling predominance at 50 and 100 fathoms, but not 75; this, both in 

 frequency and numbers, exhibits a similar predominance at 25 and 75, but not at 50. 

 It was not taken in any closing-net, and was obviously purely epiplanktonic. 



None of the above species occurred with such regularity at the surface as to enable 

 any deduction to be made with regard to a vertical oscillation. 



Taking the species together, and including indeterminable specimens : — 



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