532 



Records of the Indian Museum. [Voi,. XXIV, 



comparison can be made with allied forms in regard to the 

 structure of internal organs. However, a minute study of the 

 annulation of various similar-looking leeches from other sources 

 has led me to the conclusion that the specimens under consi- 

 deration can belong to no other genus than Trocheta Dutrochet, 



Annulation. The study of the annulation of this leech pre- 

 sented a very great difficulty. Observed in alcohol, the furrows 

 were almost invisible, the integument appearing entirely smooth 

 throughout the whole extent of the body. It was necessary, 

 therefore, to examine the specimens placed on a piece of blot- 

 ting paper and illuminated from the side, when the furrows be- 

 came visible as faint lines on the half-dried surface. 





1 



1 







% 





3 



2 





'•./ 



4- 



3 







5 



A 







v 





B 



5 









9 





- 











U 





















Text-fig. 6. — Somites xvi and xvii of 



a. Trocheta quadrioculata, sp. nov. 



b. Hevpobdella atomaria. 



The annuli are very numerous and of different widths. Ex- 

 cept at the extremities they fall into groups repeated metameri- 

 cally each consisting of a definite number of broad and narrow 

 rings'. In the middle region of the body, we find two broad and 

 seven narrow rings forming such a group, but where the somite 

 limits exactly lie, it is impossible to tell for want of proper land- 

 marks. A thorough investigation of those Herpobdellid genera, 

 whose somites exhibit annuli of unequal widths, such as Trocheta, 

 Mimobdella, and Odontobdella (as yet unpublished) enables me to 

 state with certainty, that the somite limit falls between the fifth 

 and sixth narrow rings. In other words, a somite in this species 

 typically consists of nine annuli arranged in the following order : 

 two narrow, two broad, and five narrow. Compared with the 



