4iM TV(ir, sK()('.si;i;i{(". 



J'/iilonii-iliS LiUjclumji. C <>. S\i;s. 18S(). p. 71. 



A. M. .\'ih;\i\\. ls!tl. |iji. 1 I'.), r_'l. 



(J. S. Ki;\i>\ iiiul A. M. XoKMW. ISIMI. p. ().")S, pi. \A.. \\<^^. A l<i 



C; pi. 1,11, fi,L;s. :{. 1. 

 II. 11. GkaN, 1002, ]>p. '2(1, Cd. so. I'Ki. 

 r. T. Ci-HVH. liio:?, p. i'4. 



„ ,, ( . II. OSTKM l.lli. I'.KKl, |i. 97. 



„ ,. .. .. .. and ('. Wi:si:\ii;i;(;-l.i Ml. litii!). p. 114. 



,. ,. ('. .Al'STKiN. Kill. p. Kill, pi. XXlll. fig. 4. 



Description: — F r in ale: — 



Shell: — Length 2,15 — 2,6 mm. It does not seem to be decidedly larger in northern 

 than in southern locales; a few specimens from Lofoten that I had an opportunity of investig- 

 ating had shells about 2,3 mm. long, which was the average length of the specimens from 

 Skager Rak that were investigated by me. Length : height, about 1,45 : 1; length : breadth, 

 about 1,8:1. Seen from the side (fig. 1) it is ,,rounde(l-suli-(|ua(liangnlar", with 

 its greatest height at about the middle. Tlu' dorsal margin is only weakly arched, sometimes 

 almost straight, running almost parallel with the longitudinal axis of the shell, and with broadly 

 roimded corners jjassing into the rather steeply descending anterior and jiostcrior margins. 

 The ventral margin is uniformly and moderately curved and weakly pouting just behind the 

 rostral incisur. The posterior part of the shells forms, somewhat ventrally of half the height 

 of the shell, a rather small but characteristic beak — which is perhaps the easiest means of 

 distinguishing this species from Pli. (Ph.) globosa. Above this beak-like process the 

 posterior margin of the shell is straight or very slightly arched. The rostrum has in most cases 

 a rather pointed anterior corner, which projects almost at right angles; its ventral corner is 

 rather pointed and is armed with a small spine-like process. The rostral incisur is rather deep 

 and narrow, defined from the ventral margin of the shell by a slight protuberance. Seen 

 from beneath the shell is oval with its greatest breadth at about the middle; the 

 anterior and posterior extremities are almost similar, the side contours are uniformly curved 

 (agreeing fairly well with pi. LII, fig. 4, G. S. Brady and A. M. NORMAN, 1896). The sur- 

 face of the shell is smooth, without any marked protuberances except the little spine 

 on the ventral corner of the rostrum and a very slight ridge behind the rostral incisur, running 

 out on the little protuberance, which, as has been mentioned above, marks off the rostral incisur 

 from tlie ventral margin of the shell. It has only some scattered and moderately long bristles; 

 these bristles are characterized by coming to a fine point from a rather broad basal part — they 

 are of about the same type as the long bristle in fig. 4 of Ph. (Ph.) globosa. The pores of the 

 siirface are of moderate size, rather numerous and often very difficult to observe with certainty. 

 Seen from inside (figs. 2 and 3): Medial bristles: The row of bristles on the rostrum 

 consists of a rather large number of bristles, about as in fig. 2. On the posterior portion of the 

 list there is a moderate number of bristles, partly arranged in small groups. On the part of the 

 shell between this part of the list and the margin of the shell there are a few very short bristles. 



