TWO AQUATIC OLIGOCHJETES. 3 



measurement of the chitinous penis sheath of L. gotoi Hatai is 

 not given in the original paper, but the author gives among others 

 two different figures of it — one like that of Form A (A. Z. J. 

 III., tab. II., fig. 8) and the other closely resembling that of 

 Form B (1. c. fig. 10). From these figures we may infer that 

 the chitinous penis sheath of L. gotoi Hatai is either 4 or 10-11 

 times as long as it is broad at the proximal end. 



Now an examination of the above table shows that, L. gotoi 

 Hatai resembles Form A in the prostata, anterior sperm-sac and 

 spermathecse, and Form B in the chitinous penis sheath and 

 posterior sperm-sac. 



Here it must be repeated that the three species of Limno- 

 drilus above mentioned are the only ones represented in my fairly 

 extensive collections made in different localities in Tokyo. 



These facts appear to me to prove that Hatai has confused 

 two species into one. I will, therefore, propose the name Limno- 

 drilus ivilley, n. sp., for Form A, retaining that of Limnodrilus 

 gotoi for Form B. The new name is in honour of Dr. A. Wille y, 

 to whom I owe my Indian specimens. 



Part I. Limnodrilus gotoi Hatai 1899 

 Nomura emend. 



1. Description. 



Colour of the body red, shaded posteriorly with light gray 

 or yellow. Very fine transverse striations, due to septa, in the 

 posterior part of the body. Prostomium somewhat conical. 

 Segments I-V always biannulate, anterior annulus shorter. Brain 

 almost square, emarginate posteriorly. Clitellum forming a com- 

 plete ring, usually in segment XI, but sometimes extending from 

 segment JX to segment JXII, or from segment XI to XII, both 

 entirely inclusive. Setae sigmoid, bifurcate at end ; lower branch 

 strongly and upper slightly curved ; both almost equal in length 

 under a low power. Each seta-bundle mostly consists of 6 setae 

 in the anterior segments, of 3-5 in the middle segments, and of 



