studies on inarino Ostracods 411 



The posterior part of the shell is, at about a third of the height of tiie shell, drawn oiit into 

 a well-marked, almost rectangular, and in most cases rather pointed, corner — sometimes, however, 

 somewhat less pointed than in the accompanying figure. Above this corner tbe posterior margin 

 of the shell is very weakly concave or almost straight. The rostrum has a rather strongly pro- 

 jecting, almost rectangular, but rounded, anterior corner; its ventral corner is about of the same 

 shape as the anterior one and has an exceedingly small, almost completely reduced, spine. The 

 incisur is rather narrow and deep, and not, as in Ph. (Ph.) globosa, Lilljeborgi and several other 

 species of this genus, marked off from the ventral margin of the shell by a protuberance. Seen 

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

 and posterior ends being almost symmetrical, the side contours uniformly curved. The s u r- 

 f a c e o f t h e s h e 1 1 is, at least partly, covered with small, rounded, shallow, rather close 

 foveolae, in most cases difficult to observe, but apart from these it is quite without sculpture. 

 It has rather sparse, scattered and rather long bristles, somewhat more numerous near the 

 margin of the shell; these bristles are characterized by the fact that they suddenly grow narrower 

 from a rather thick basal part (of about the same type as the long bristle in fig. 4 of Ph. (Ph.) 

 globosa). The pores of the surface are difficult to observe, rather small and numerous. Seen 

 from inside: Medial bristles: The bristles in the row on the rostrum are rather numerous 

 (about the same as in figs. 2and 6 of Ph. (Ph.) Lilljeborgi). On the posterior part 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 bristles (of about the same type 

 as in fig. 3 of Ph. (Ph.) Lilljeborgi). There is no such pocket as characterizes this latter species. 

 The selvage on the rostrum has short, marginal hairs. 



First antenna: — The three bristles on the second joint are most frequently 

 subequal and about as long as the fourth joint. Either all the bristles or one of the two anterior 

 ones and the posterior bristle on the third joint were without long secondary bristles in the 

 case of the specimens investigated by me. The same was true of the a-bristle on the end joint. 

 Each of the other bristles on the second to the fifth joints had only one wreath of long, stiff secon- 

 dary bristles at the middle. Otherwise this antenna agrees very closely with that of Ph. (Ph.) 

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



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

 The bristles on the second to the fifth joints are about as long as the total length of the two 

 or three proximal joints and are furnished at about the middle with a series of about ten rather 

 strong, smooth ventral spines. The long natatory bristles were unbroken in the females in- 

 vestigated by me, although some of these had rather large eggs in their brood chambers. 

 Endopodite (fig. 2): The first joint is of the same type and has the same equipment of 

 bristles as this joint of Ph. (Ph.) globosa. The second joint is rather elongated and has two 

 bristles ventraUy, somewhat proximallv of the middle, the one situated somewhat proximally 

 of the other. The proximal one of these bristles is rather long and has several wreaths of long, 

 stifi secondary bristles at the middle and short hairs distally. The distal one is rather short 

 and has only short hairs. The end bristle on this joint is somewhat longer than the joint and 

 is finely rounded distally. 



