On some Pericliatidsp from Japan. 757 



those of the gizzard segments being absent. The missing septa are 

 those which sliould divide segments VIII IX and IX X. There are 

 four recognizable septa in front of the gizzard. The first four of those 

 lying behind the gizzard are strongthened, but their increase in thick- 

 ness over those which follow is not very niarked, There are the usual 

 four pairs of dilated hearts in segments X — XIII (inclusive). The 

 nephridia are in no way remarkable, being of the ditiuse kind iuvariably 

 met with in the genus Perichceta (s. s.) ; in some of the anterior segments 

 there is a marked increase of the nephridia, which also occurs in most 

 if not in all of the species of this genus. 



The alimentary canal again is not ditferent from the alimentary 

 canal of other PericlKEtce \ the Oesophagus wideus out in the Vllth 

 Segment to form a kind of crop; the gizzard immediately follows the 

 crop, and appears to occupy three segments; but, judging from the 

 analogy offered by other species, it probably corresponds to two 

 segments only, the Vlllth and IXth. Owing to the absence of the 

 septum, which should divide segments IX X, it looks as if the gizzard 

 extended into the Xth segment, but a careful examination of the organ 

 itself shows that its walls become thiiiner and more membranous in 

 structure l)efore the end of the Xth segment, so that this section 

 of the gut may be fairly regarded as belonging to the Xth segment. 

 In segments XII, XIII and XIV the walls of the Oesophagus are mucli 

 thickened and pinkish in appearance; this region of the cesophagus 

 probably corresponds to the calciferous pouches of other earthworms, 

 which are not otherwise represented in this or other species of the 

 genus. The large intestine commences in the XVth segment. In- 

 stead of possessing the usual pair of cteca in the XXVIth segment 

 this species has 6 to 8 pairs of diverticula of the gut in that segment. 

 l'hese are shown in Fig. 4. These numerous cieca spring fiom tiui 

 side of the intestine close to each other, the series of each side form- 

 ing a straight line transverse to the longitudinal axis of the gut. Of 

 these cieca the upperraost one on each side is very much the largest 

 of the series. This peculiar arrangement of the cjeca has been 

 recorded before in Perichceta, in P. sieboldi, by Dr. Hokst*). üp to 

 the present that species and the one described in this paper are the 

 only two which show this remarkable peculiarity. 



The most interesting peculiarities of Perichceta roJcuyo, however, 

 coücern the structure of the reproductive organs. The male repro- 



1) loc. cit. 



