THE AMPHIPODA. 49 



Hyperioides longipes, Chevreux. 



The table of occurrences of this species (p. 53) shows conclusively that at the time 

 of our cruise, and in our area, the 100-fathom horizon was the centre of its vertical 

 distribution. It occurred in : 



86 per cent, of the 22 hauls at 100 fathoms, 

 36 „ „ 11 „ 75 „ 



15 „ „ 13 „ 50 „ 



U ,, ,, ~o ,, U ,, 



and in the two closing hauls 21 n (150 to 100) and 21 p (150 to 50). It occurred in not 

 one of the 35 " comparable " hauls which closed at various depths below the 100-fathom 

 line. The serial hauls 36 g, h, i, ajid k were open tow-nets, and may possibly have 

 captured it at any depth less than that to which they were lowered. It is not certainly 

 apparent from the table that the species rises particularly at night. 



The captures by the ' Hirondelle ' seem to point to a greater depth, but they would 

 have carried more evidence had any one of them included more than a single specimen ; 

 they were as follows : — 



The species described by Vosseler as Hyperia sibaginis ? does reach the surface rarely ; 

 it was captured by the ' National ' on 41 occasions, of which no less than 92 per cent, 

 were in vertical, plankton, or other open nets from between 273 or 109 fathoms to the 

 surface ; but it was taken at the surface only twice in the open ocean, once in brackish 

 water in the Tocantins (mouth of Hiver Para). Mr. Walker records it from the 

 ' Oceana ' collections as having been taken in open nets lowered to 150 and to 

 510 fathoms. 



Parathemisto oblivia (Kroyer). 



Owing to the small size of the specimens, Mr. Stebbing expresses himself as not 

 quite certain of the identification. It is noticeable from the table (p. 51) that as it 

 never appears in any of the 22 hauls at 100 fathoms, these small specimens, unlike 

 Syperioides longipes just mentioned, probably do not live at that depth ; in that case the 

 single specimens from 21 vi, 21 ii, and 21 o were jierhaps adopting a mesoplanktonic 

 habitat ; for from the evidence which I have previously adduced t, it seems likely 

 that this supposedly northern species is epiplanktonic when young, mesoplanktonic 



* The " filet a ressort " is probably that of Baron do Guerne ; the " filet k gouvernail " seems to be the " filet 

 bathypelagique " of the Prince of Monaco. 



t Proc. Zool. Soc. 1898, p. 583, & 1903, i. p. 126. 



