4U TACR SKOr.SHKItn 



Ph. (Philotnedcs) rotunda n. sp. 



Dvscriptwii: — F o in u 1 o: — 



Shell: — Length, 1,9 — 2,1 mm.; U'ngtli : heiglit about 1,;J : 1; U'ligth : hicadtli about 

 l.ti : 1. S c t> n f r o m t li c s i d o (fig. 1) it has a broad oval shape, with its posterior part 

 somewhat larger than the aiitirinr jiart. the greatest height being at about the middle. The 

 dorsal, posterior and ventral margins are uniformly rounded, passing into each other without 

 anv corners; the ventral margin is weakly pouting just behind the incisur. The rostrum has 

 a broadly rounded anterior corner, its ventral corner is rather pointed, but is witliout any 

 spine (such as we find, for instance, in PIi. (Ph.) globosa, Lilljehorgi and other species of this 

 sub-genus). The incisur is moderately deep and narrow, and is not marked off from the ventral 

 margin of the shell by any protuberance (cf., foi- instance, Ph. (Ph.) qlohosa and Lilljehorgi). 

 Seen from beneath it is oval, with its greatest breadth at about the middle, the anterior 

 and the posterior ends rather broadly (more so than in Ph. (Ph.) globosa, for instance; cf. the 

 figure for this species) and almost symmetrically rounded; its side contours are uniformly arched. 

 Surface of the shell: This has no marked sculpture; in transmitted light it appears to be 

 rather finely and irregularly reticulate (cf. fig. 2); in reflected light each mesh seems to correspond 

 to a rather shallow cavity. It is sparsely furnished with moderately long, scattered bristles, 

 which are characterized by suddenly becoming narrower from a rather broad basal part (their 

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

 are rather small and numerous and very difficult to observe with certainty. Seen from 

 inside: Medial bristles : The bristles on the rostrum are about as numerous as on Ph. (Ph.) 

 LiUjeborgi; most of them seem not to have any long hairs distally. Posteriorly on the list 

 there are a moderate number of bristles, partly arranged in small groups. Between the 

 posterior part of the list and the margin of the shell there are a few short bristles. On the other 

 hand there is at this place no such pocket as has been given as characteristic of Ph. (Ph.) LiUje- 

 borgi. The rostral selvage has rather short marginal hairs. 



First antenna (fig. 3) : — This agrees in its details with this antenna of Ph. (Ph.) 

 globosa. No variation was observed in the number of sensorial filaments on the end bristles. 

 There are rather abundant hairs on the second joint, and short, stiff hairs were also observed 

 on the first joint, especially ventrally. 



Second antenna: — Exopodite: This is very like that of Ph. (Ph.) globosa. 

 The bristles on the second to the fourth joints are about as long as the first joint. In females 

 with large eggs in the brood chamber the long natatory bristles were broken off as in the species 

 just mentioned. The e n d o p o d i t e is also very like that of Ph. (Ph.) globosa. Sometimes 

 a rather short bristle, with short hairs, may be found somewhat distally of the long ventral 

 bristle on the second joint. The distal bristle on this joint is perhaps somewhat more pointed 

 than in Ph. (Ph.) globosa. 



Mandible: — P r o t o p o'd i t e: Basale: This has from seven to nine bristles 

 ventrally, some of which are rather long and some of moderate length. Apart from the two 



