Pliiloinedes hreiida C. H. Ostknfklk. HMMi, p. kt. 

 A. K. l.l\l\0. 11»(I7. |i. l!i:>. 



(". H. OSTENFKLD ami C \\'i:si:\ |;i:KCi-LUNl), l!t()!t. ].. 114. 

 A. M. NOIOIAN and V,. S. l5l;\M^. l!t(i<i, p. :WX 

 (i. (>. 8AKS. liton. p. 4(t. 

 ('. Apstkln, 1911, p. lus. \'\. XXIII. 

 (i. \V. MCller, 1912. p. 32. 

 glohostis, K. StEPIIENSEN, 1912, p. 551. 

 hioifld. „ „ 1913. ]). 353. 



1917. p. :{n(5. 



Description: — Fein ale: — 



Shell: — Length 2,3 — 3,1 mm.; only specimens from the most northern locales, Greenland, 

 Spitzbergen etc. have shells as long as 2,9 — 3,1 nun.; the specimens from the more southern 

 locales are, on the average, rather considerably shorter; thus, for instance, the specimens from 

 Skager Rak that were investigated by me were, on un average, only about 2,4 — 2,6 mm. 

 Length : height, about 1,4 : 1; length : breadth about 1,75 : 1. Seen from the side, 

 (tig. 3) it has a somewhat varying shape, though the variation is rather slight. The greatest height 

 is at about the middle. The dorsal margin is rather weakly arched; this arching is, however, some- 

 what different in di fferent individuals ; it is somewhat sloping posteriorly and with broadly rounded 

 corners passes over into the rather steeply sloping anterior and posterior margins. The ventral 

 margin is imiformly and moderately strongly curved and is somewhat pouting just behind the 

 incisur. The posterior part of the shell forms a rather slightly projecting and somewhat rounded 

 corner somewhat ventrally of half the height of the shell; above this corner the posterior margin 

 of the shell is straight or is only slightly arcuated. The rostrum has a more or less rounded 

 anterior comer, projecting in most cases almost at a right angle; its ventral corner is rather 

 pointed and has a small spine-like process. The rostral incisur is rather deep and narrow and 

 is defined from the ventral margin by a weak protuberance. Seen from below the shell 

 is oval, with its greatest breadth at about the middle, the anterior and posterior ends of about 

 the same shape, the side contours almost vmiformly curved (about the same as in the accom- 

 panying figure 2 of the male). The surface of the shell has no marked protuberances 

 except one weak ridge behind the rostral incisur, continuing on to the above-mentioned small 

 protuberance that forms a boundary between the ventral margin of the shell and the incisur, 

 and the small .spine on the point of the rostrum. It is covered with numerous rounded cavities, 

 situated fairly close together; these are very often difficult to discern, especially on the specimens 

 from the more southerly locales, and sometimes they even seem to be quite absent. The whole 

 surface has scattered short, stiff bristles, situated rather close together; among these there are 

 also a few som^ewhat longer bristles, distinguished by the fact that from a short rather thick 

 basal part they taper to a fine point (these bristles are, however, not quite so long as those on 

 the shell of the males), see fig. 4. The pores of the surface are very difficult to discern with 

 certainty in most cases; they are rather small and numerous. Seen from inside: Medial 



