HIRUDINEA FROM THE INLE LAKE, S. SHAN 



STATES. 



By Asajiro Oka, Tokyo. 



(Text-figs. 1-7.) 



The collection of leeches from the Inle Lake, S. Shan States, 

 kindly placed in my hands for study by Dr N. Annandale, is a 

 small one, comprising only three genera and five species. It is 

 nevertheless of an exceptional interest on account of certain 

 structural peculiarities exhibited by some of the new forms, which 

 seem to throw considerable light upon the question concerning 

 the external morphology of the Hirudinea in general. 



One of the new forms, Glossiphonia inleana, sp. nov., is 

 unique among" the Glossiphonidae in having the three annuli 

 constituting a somite easily recognizable at a glance. As is well 

 known, the external annuli of the Hirudinea have, as a rule, an 

 exactly similar appearance, making the determination of somite 

 limits a matter of great difficulty. Until so late as 1900, when 

 Castle (5) and Moore (n) almost simultaneously pointed out its 

 inadequacy, an entirely erroneous method of plotting out the 

 somite limits by assuming the sensillae-bearing annulus to be 

 the first annulus of the somite, was in use among students of 

 leeches. Now, in our species, there is no danger of being mistaken 

 in the determination, as the furrows separating the somites are 

 decidedly deeper and more conspicuous than those separating the 

 annuli of the same somite. This is particularly apparent at the 

 maigins of the body, where the rings form groups of three each, 

 two fused together and one separate, projecting toward the side 

 in the form of broad and narrow teeth placed alternately. 



Another new species, Glossiphonia annandalei , is also very 

 interesting because of its having four of the six eyes arranged 

 transversely upon one and the same annulus. This character, 

 though not uncommon among the Herpobdellidae, has, so far as I 

 know, never been observed in any of the remaining families. 



The five species dealt with in the present paper are here 

 systematically arranged : — 



Family Glossiphonidae. 



Glossiphonia heteroclita (L/inne). 

 Gl. inleana, sp nov. 

 Gl. annandalei sp. nov. 

 Piacobdella parasitica, juv. (?) 



