On some Pericliwtidre from Japan. 759 



other species of the genus in the total absence of 

 atrium or aiiy copulatory apparatus connected with the 

 m a 1 e'5'p o r e s , and is so far absohitely unique in the geniis. The 

 vasa deferentia theraselves were quite obvious on account of their 

 white colour; I traced them as far back as the XXth segment (the 

 XXIInd in one specinien) upon which they appear to opeu ; but I 

 have not so far succeeded in finding the actual orifice on to the 

 exterior. This species oi Ferichceta is therefore peculiar 

 not only in the absence of the atrium but also in the position of 

 the male pores, which lie several Segments behind 

 the XVIIIth, which segment as a rule bears the orifi- 

 ce s. There are two pairs of spermatothecfe in Segments VII and 

 VIII, each of which consists of a largish oval pouch borne on a 

 stalk, the duct; a long diverticulum having the form illustrated in the 

 Figure 2, opens into the duct near to its external orifice. In the Vllth 

 and Vlllth segments there is a mass of capsulogeuous glands (Fig. 5), 

 each borne on a longish stalk opening on to the exterior by the aiea 

 already referred to on the Vlllth segment. The structure of one of 

 these glands is shown in Fig. 3. 'Jlicy consist, as these glands always 

 do, of a mass of pear-shaped cells bound together by a sheath ; 

 each individual cell is prolonged into a fine process, which serves as 

 its duct. 



The ovaries and oviducts occupy the usual position ; there are 

 two pairs of egg-sacs in segments XIII and XIV. 



J^erichieta sieboldl Horst. 



Perichceta sieholdi Horst in: Notes fr. Leyd. Mus., Vol. 5, p. 191. 

 Perich^eta sieholdi Rosa in: Ann. k. k. Naturh. Hofmns., Bd. (i, p. 401. 



The collection contained one exaniple of this sjjccies, which is 

 now — through the researches of Des. Horst and Rosa — a well known 

 form. My specimen measured 4* ., inches in length and 7 mm in 

 diameter posteriorly; it consisted of 74 segments. It is therefore a 

 much smaller individual thau aiiy of those previously examined. It 

 might be inferred that this difference was siniply due to the degree 

 of relaxation of the worms: were it not certain from the number of 

 Segments that there is really a difierence in size. The examples 

 stiidied by my predecessors ranged in length from 135 to 145 segments. 

 As there is, so far as we know at present, a fixed size, only varying 



