296 ASAJIRO OKA; ON SOME NEW 



canal is very nearly allied to that in Herpohdella. In both genera the 

 nephridial canal consist.«^ of a large number of cells arranged in a 

 single row, Mud perforated in the direction of the row so us to form 

 drain ])ipes. For the greater part of the length, where two or three 

 rows of cells come to touch each other, these pipes coalesce, the 

 boundary between their walls becomes less distinct, and the whole 

 structure appears in sections, as if it consisted of only a single row of 

 cells perforated by two or three canals. In this resj)ect, what I des- 

 cribed for Glos.^(mp]ionia applies equally well to Orohdella or Herpohdella. 

 A figure of the iie])hridiura of Herpohdella octoculata (Linné) 1758 

 (=Nephelis cuhjavis Moq.-Tand. 1827) as reconstructed from sections 

 by A. Graf (1893), represents the canal as running from the capsule 

 to the bladder in a simple course, but this is decidedly false. In 

 Herpohdella as well as in (Jrohdella, the canal makes at least three 

 loops, and those portions of the diiferent loops thîit come to run 

 parallel to each other coalesce in the manner above described. 



At the distal end of the nephridial canal there is a bladder-like 

 dilatation lined wifli ciliated epithelium. Its shape is generally 

 conical witli the aj)ex pointing toward the integument (Fig. 4., PI. 

 XXX). Whitman (188()) found that the land leech he investigated had 

 large bladders as compared witli the medicinal leech, and expressed the 

 opinion that the large size of these organs is probably a result of 

 ada|)taticjn to the terrestrial mode of life. As this seemed very 

 interesting, I examined the bladder of Orohdella in comparison to 

 that of Herpohdella^ which is undoubtedly its nearest aquatic ally, but 

 my results were all negative. Orohdella has only as large bladders as 

 Herpohdella or even smaller than them. It is not, therefore, every 

 form of terrestrial life that causes the enlaruement of bladder but onlv a 

 certain kind of terrestrial life. There are essentially only two different 

 modes of life among the land leeches, one represented by Hœinadipsa and 



