Report on the Malacostraca, P^Tnogonida and some Entomostraca. 607 



Further, the parasites are also taken here, if their hosts belong to 

 the open sea (Cyamus, Æga, Dajidae). There remain a couple of 

 uncertain species, namely, the Amphipods Apheriisa glacialis and 

 Eurytenes gryllus. The former seems certainly to belong to the open 

 sea; but as it has been at least several times met with in among 

 the drift-ice, it is included under the littoral forms (Group 3C., 

 p. 586). The case is more difficult with Eurytenes gryllus; but, for 

 reasons to be given later, it must be referred to the plankton. 



The plankton may be divided into an essentially arctic and an 

 essentially boreal group, but for the moment we are in great need 

 of hydrographical material, so that future investigations will cert- 

 ainly make great changes in the lists below, among other things, in 

 the direction of removing from the one list to the other; there seems 

 to be no doubt, that there are very few, really arctic species among 

 the plankton Malacostraca, that is, species which exclusively or 

 mainly live in water of negative temperature. Most of the distinctly 

 arctic forms will certainly prove to be rather bottom-animals than 

 plankton-forms. 



4 A. Plankton species which are mainly arctic. 



Boreomysis nobilis. Stilomysis grandis. 



Erythrops abyssorum. Mysis oculata. 



— glacialis. Lanceola Clausii. 



Meterythrops robusta. Euthemisto libellula. 



Parerythrops spectabilis. Cyclocaris Guilelmi. 



Amblyops Crozetii. Cyamus mysticeti. 

 Pseudomma frigidum. — monodontis. 



— truncatum. — nodosus. 



— Theelii. Dajus mysidis. 



Boreomysis nobilis has been found at a number of places in the 

 Davis Strait N. of 63^24' N., 892 m. (H. J. Hansen 1887, '^Tjalfe"), but 

 seems otherwise to belong to the cold area Avith the coasts. 



Erythrops abyssorum ranges from W. Greenland over Norway to 

 the Kara Sea and goes south as far as north of the Hebrides (59° 

 25' N. — 59°36'N.), 1100— 1060 m., 7.10°— 7.22^ C. (Tattersall 1911). 



Erythrops glacialis is known from E. Greenland and the middle 

 of the Norwegian west coast in the cold area. 



Meterythrops robusta has been taken in the Davis Strait 68°40' N., 

 53°12'W., 410 m., 350 m. wire ("Tjalfe") and in Massachusetts Bay; 

 elsewhere it belongs to the cold area with coasts and the Kara Sea. 

 The record of its occurrence at W. Ireland (Holt and Tattersall) is 



