THE SCHIZOPODA, 



129 



may account for the failure to take Mcganyctiphanes norvegica by day, but it does not, 

 to ray thinking, explain away the apparent nocturnal rise of Euphmisia Millleri. 



Summary. 



The following conclusions, relative to the more plentiful species, refer, of course, only 

 to the area studied and to the time of the cruise. They are not necessarily, many of 

 them not even probably, true for distant localities under different conditions. 



None of the species captured throw any light on the population of the Mesoplankton ; 

 all those taken in any quantity were essentially epiplanktonic. But Euphausia 

 Mi'dleri ranged as deep as 250-150 fathoms, Nematoscelis megalops doubtfully to 400- 

 300 fathoms. Eiicopia tmguiciduta, a purely mesoplanktonic form, occurred as high as 

 200-100, and as low as 750-500 fathoms. 



JEuphausia JJiilleri was essentially epiplanktonic, with a centre of distribution at 

 about 50 to 75 fathoms. It appeared to descend in small numbers as far as 250-150 

 fathoms. At the surface and 25 fathoms it was captured only by night, and in large 

 numbers by moonlight : it may be regarded as an instance of a nocturnally rising 

 species. 



Megaiij/cf/phanes norvegica, caught comparatively in small numbers and on few 

 occasions, was j^urely epiplanktonic, and was captured only by night. 



Nematoscelis megalops was essentially epiplanktonic, with a centre of distribution at 

 about 50-75 fathoms ; a few specimens were caught at greater depths than 100 fathoms. 

 The indications of a nocturnal rise were less well marked than in Euphaiisia Miilleri. 



Stylocheii-on Suhmil was the species most numerously and most frequently 

 represented in the collections. The centre of distribution lay again at about 50 to 

 75 fathoms ; and it is doubtful whether the species penetrated much below ]00 fathoms. 

 The expectation of larvae diminished, and that of adults increased, with depth down to 

 100 fathoms : larvne were captured in greater numbers by day, adults by night. The 

 indications of a nocturnal rise were not strongly marked. 



Stylocheiron ahhreviatum, taken rarely and in small quantities, was confined to nets 

 towed at 75 and 100 fathonas. 



