132 



half the length, dorsal margin rather evenly arched and sloping gently behind, 

 ventral margin almost straight, anterior extremity broadly rounded off, posterior 

 somewhat narrower and obtuse at the end; seen dorsally, broadly fusiform 

 in outline, with the greatest width in the middle and about equal to half the 

 length, both extremities pointed and nearly equal. Surface off shell densely 

 clothed with rather coarse hairs. Natatory setae on the posterior antennae 

 scarcely extending beyond the middle of the succeeding joint. Spines on 

 outermost masticatory lobe of the maxillae armed near the extremity on each 

 side with 2 opposite strong denticles. Caudal rami resembling in structure 

 those of the preceding species. 



Colour dark fuscous, with a bluish green shadow dorsally behind the 

 ocular region. 



Length of adult female 1.60 mm. 



Male unknown. 



Remarks. This form was at first (1866) confounded by me with the 

 preceding species, to which it certainly bears some ressemblance in its general 

 appearance. It was however subsequently subjected to a closer examination, 

 and its specific distinctness thereby ascertained. It is of much smaller size and 

 moreover distinguished by its more tumid and densely hairy shell, as also by 

 its somewhat different colour. 



Occurrence. This is a true arctic species, being almost exclusively con- 

 fined within the polar circle. The specimens at first observed vere taken 

 during the Norwegian North Atlantic Expedition in small water-holes at Advent 

 Bay, Spitsbergen. Subsequently I was enabled to include this form also in 

 the Norwegian Fauna, having taken some specimens at Smelroren, on the 

 mainland inside Vard0, East Finmark. According to Dr. Aim, this form has 

 also been met with, as a glacial relict, on the high-plateau of Filefjeld (Jotun- 

 heimen). 



Distribution. Greenland, Spitsbergen, Bear Island, Nowaja Zembla, Swe- 

 dish Lapmark. 



53. Prionocypris pigra (Fischer). 



(PI. LXI, fig. 2). 



Cypris pigra, Fischer, Mem. Soc. Imp. de St. Petersbourg, Vol. 7, p. 158, PI. 9, figs. 111 

 Syn: Cypris tumefacta. Brady. 

 ,, Herpetocypris tumefacta, Brady & Norman. 

 Eucypris pigra, Aim. 



"" 



Specific Characters. Female. Shell very tumid, seen laterally, oval 

 trigonal in shape, greatest height nearly in the middle and considerably ex- 



