200 



Records of the Indian Museum. 



[Vol. VI, 



a certain similarity in structure to the gizzard of that genus 

 (pi. xiii, figs, 12, 13). Its function is however totally different, 

 and it differs structurally in not possessing horny internal teeth. 

 Moreover, the walls do not contract automatically with the retrac- 

 tion of the poh'pide as the}- do in the gizzard of Bowerhankia. 



Freder'ic ell a 



^f.LUOlCfi_^, 



The spherical chamber in the alimentar^^ canal of Hislopia is not 

 a crushing organ but serves as an antechamber in which food may 

 be stored until it is wanted for digestion. In it also the flagellate 

 organisms that seem to form the greater part of the food undergo 

 a process of encystment in the course of which food-material is 

 pressed out from their bodies and apparentl}^ absorbed by the 

 polyzoon. Further details as regards this process are given on 

 pp. 200 — 202 of my volume in the '' Fauna of British India." 



Two forms which I believe to be merely varieties or at most 

 local races (subspecies) of H. lacustris have been described as 

 distinct species. They are — 



