CEUSTACEA OF NEW ZEALAND. 197 



therefore to the lemale only, though doubtless it will apply equally well to the male, 

 except as regards the lirs>t and fourth appendages of the perseon and the second pleopoda, 

 which are specially modified in the male. 



I described this species pretty fully in my original paper [23], and in the present 

 paper I have given a full detailed description of the new species P. assimilis, and I 

 shall therefore give only such further details of P. typicus as arc necessary to exhibit 

 clearly the differences bct\\een the two species. 



Body (PI. XVIII. lig. 1). It will be seen, from a comparison of PI. XVI. fig. 1 and 

 PI. XVIII. fig. 1, that the body is much more slender than in. P. assimilis ; thus iu one 

 ^l ecimtn that I have mounted dry on a slide, and from which fig. 1, PI. XVIII. is taken, 

 the body is fully 15 mm. long, yet the depth is only 1"5 mm., the same as the depth of 

 a specimen of P. assimilis that was only 10"5 mm. long. 



The surface of the whole body is smooth, and though there are a few fine setae 

 scattered over it, chiefiy in the plcon, they are not so numerous nor so distinctly 

 arranged in small tufts as in P. assimilis. 



Perceon (PI. XVIII. fig. 1). The first segment is very short, not half so long as the 

 succeeding; it widens inferiorly, and has the inferior angle somewhat produced and brought 

 close up to the head, so that the first pair of appendages of the perteon seem almost to 

 arise from the head. The next three segments arc subcqualand rather longer than deep ; 

 they are quite rectangular in outline, the inferior margin being almost straight and 

 scarcely hollowed, except slightly in the first segment for the reception of the coxa of 

 the appendage, which is small and placed well to the anterior end of each segment. 

 The next three segments are similar, but each is shorter than the jircceding segment ; 

 the inferior margin of each is emarginated towards the posterior end for the triangular 

 coxa. 



Pleoii (figs. 1, 11). In the pleon this species resembles P. assimilis as above 

 described, but the pleural portions are not so largely developed, being somewhat 

 shallower than their respective segments, and their inferior margins are more abundantly 

 supplied with setae. In each segment there is a slight ridge where the pleural poi-tion 

 IcaAcs the bodj-ring pioper, but the integument is quite continuous, and there is no 

 suture or line of division of any kind. 



Ihe projection at the end of the telson (fig. 12) is narrow, longer than broad, projects 



slightly upwards, and has the truncate extremity tipped with a few setaj ; there is a 



stout seta below at its base ; the inferior margin of the telson on each side from this 



jirojection to the articulation of the uropoda is irregular and fringed with very fine 



setae. 



The vpper unlenna (fig. 2) extends a little beyond the extremity of the third joint of 

 the peduncle of the lower antennae ; it usually contains eight joints, but is not distinctly 

 divided into peduncle and flagcllum. The first three joints are similar, but each smaller 

 than the preceding, oblong, about twice as long as broad, with a few setae at the distal 

 end ; the fourth joint is like the third, but shorter ; the fifth shorter still, but somewhat 

 expanded distally ; the sixth and seventh are subequal to each other and to the first joint 

 and are considerably swollen ; the eighth joint is usually small, but swollen ; the last 



20* 



