402 OLIGOCHAETA 



Pacific islands. The remaining fifty (roughly) are confined to the oriental region, which 

 is clearly the head-quarters of the genus. 



In reviewing the structure of the different species there does not appear to be 

 much correspondence to be traced between structure and distribution. The most marked 

 instance of any such connection is to be seen in the Japanese species of the genus. 

 There is a distinct tendency among the Japanese Perichaeta for the glandular part 

 of the spermiducal glands to disappear. The occasional existence of six intestinal 

 caeca in place of the usual one is another feature of the Perichaeta of this part of 

 the world. 



In addition to the species described in tlie following pages, there are a number of Perichaeta, 

 which cannot be adequately defined, although it is fairly certain that they belong to the genus 

 Perichaeta (s. s.). Many of them are probably synonymous with species which are well characterized 

 under other names. Those species inquirendae are as follows: — 



Megascolex diffringens, Baikd, England. 

 Perichaeta juliani, Peeeieb, Saigon. 

 Perichaeta bicincta, Peeeiee, Philippines. 

 Amyntas aeniginosiis, Kinbeeg, Guam. 

 Ehodopis javanica, Kinbeeg, Java. 

 Perichaeta suhguadrangula, GeubE, Viti. 

 Perichaeta rodericensis, Geubb, Rodriguez. 

 Perichaeta tricystis, Peeeiee, Brazil. 

 Perichaeta dicystis, Peeeiee, Brazil. 

 Nitocris gracilis, Kinbeeg, Rio Janeiro. 

 Perichaeta viridis, Schmaeda, Ceylon. 

 Megascolex sanctae-helenae, Baied, St. Helena. 



None of these species are characterized sufficientljj to enable their distinctness from those fuJly 

 described here to be ascertained ; but it seems to be the fact that they all belong to the genus Perichaeta. 

 In several cases there are no positive data which render this conclusion absolutely certain. For 

 instance, P. dicystis and P. tricystis have only been defined by the number of their spermathecae ; 

 it is their habitat which leads me to place both in the genus Perichaeta. So too, with regard to 

 Nitocris gracilis. P. mridis I have examined myself and believe to be a true Perichaeta. 



P. rodericensis is described as possessing a clitellum of only two segments, as has also P. hicincta. 

 I have found myself that P. tipoluensis is constantly in the same condition, but I am at present 

 inclined to doubt whether this is a distinctive character. I fancy too that the location of the 

 male pores of P. rodericensis on the seventeenth segment is not right ; if it prove to be correct, 

 then, of course, this species will at once become a 'good' one. 



I am inclined to fancy that Megascolex diffringens is P. indica; the latter has been met with in 

 hot houses in this country. At any rate, the woodcut of the worm given by Baied shows that it is 

 a true Perichaeta. 



P. juliani is stated to have continuous setae, a clitellum consisting of three segments commencing 

 with the fourteenth, three to seven pairs of papillae after the male pores, and four pairs of 

 spermathecae. This is not quite enough to distinguish the species. 



