48 



DE. G. H. FOWLER— BISCATAN PLANKTON : 



in the comparatively warm water of the Mediterranean, seem to be the lowest strata to 

 which a net containing Scina crassicornis has been lowered, hut it has yet to be shown 

 that it reaches these not very considerable depths in the Atlantic. 



Speaking of the Scinidse as a whole. Dr. GarboM^ski says that they exhibit " bathy- 

 metrische Indolenz und Eury thermic " ; and till closing-nets are more used we must be 

 content with such general statements. But it must he borne in mind that the ' Pola ' 

 worked in the Mediterranean only, a " closed sea " where the decrease of temperature 

 with depth is very slight when compared with that in the open ocean ; and that at the 

 lowest depth with a closing-net from which Garbowski obtained crassicornis, viz. 

 273 fathoms, the mean temperature is about 56°. A species may be markedly eurybathic 

 in the Mediterranean without being correspondingly eurythermic. 



At the same time some species of Scinidte, e. g. Clausii, are apparently eurythermic ; 

 but the family seems as a whole to dislike very cold water, since not a Scina was recorded 

 by the Norwegian North Atlantic Expedition. The single exception, the one outlier to 

 the North at present known, is Scina borealis. 



Scina borealis (Sars). 



This appears to me to he one of the most interesting finds. Its previous records are 

 most easily expressed in a table : — 



It seems to be most unlikely that it occurs at the surface or moderate depths in the 

 North Atlantic, as neither the ' Hirondelle,' ' National,' nor ' Buccaneer ' met with it. I 

 cannot but think that it will prove to be a purely cold-water form, seeking its optimum 

 temperature at considerable depths in low latitudes. 



