igai.] N. Annandale & R. B. S. SeweIvL: Vivipara. 287 



show that the normal food of Vivipara bengalensis consists 

 ahnost entirely of algae and minute particles of vegetable matter 

 which are rasped off from the surface of submerged plants, stones, 

 decaying vegetable matter, etc. Along with these fragments of 

 vegetable origin, a considerable quantity of fine mud and sand is 

 ingested and swallowed in consequence of which the bulk of faecal 

 material is very large. After passing up the oesophagus the food 

 is mixed in the stomach with the bile which is poured out by the 

 hepatic ducts, so that the stomach contents have a brown 

 appearance and are liquid in character. As the contents are 

 passed down the intestine, they become more and more solid and 

 are finally moulded into small oval pellets which are at first usually 

 rounded at one pole and more or less acutely pointed at the other. 

 Later on, however, both poles become rounded. Finally these 

 pellets are ejected through the anus into the syphonal tube and 

 are forcibly swept out of the body by the outflowing current of 

 water. 



At times individuals have been found whose stomach and 

 Intestine were crowded with enormous numbers of a species of 

 Volvox. These invariably contained within the parent colony a 

 number of daughter colonies, and it is interesting to note that 

 although the superficial cells of the parent colony were digested, 

 the daughter colonies, being more deeplj^ seated, entirelj' escaped 

 digestion, and passed out of the body in the faeces in apparently 

 a perfectly healthy condition. Gravely [vide Annandale, 1911, p. 

 216) has noted a somewhat similar phenomenon in the fresh- 

 water polyzoon, Plumatella re pens. 



If aquatic vegetation is not available, as was the case where 

 examples were kept in earthen basins or glass bowls, the animals 

 could frequently be seen rasping oiT the algae that were growing 

 on each others shells. 



Although normally vegetable feeders, this Vivipara is by no 

 means averse to a carnivorous diet, and feeds on the bodies of 

 other dead snails. This habit appears to be by no means uncom- 

 mon in molluscs that are normally vegetable feeders. Benson 

 (1829, P- 363 and T830, p. 126) has called attention to the carni- 

 vorous habits of a species of Pahidina, under which generic term 

 Vivipara was formerly included, but from his description of the 

 animal it seems probable that he was referring to a species of 

 Bithynia or Ainnicola. Baker (1911, p. 42) has also pointed out 

 that Limnaea is at times carnivorous though normally a vegetable 

 feeder, but his statement that " the part they play as natural 

 scavengers renders their presence in water-troughs and other 

 sources of drinking water highly desirable " seems to overlook 

 the fact that the presence of these snails may be and almost 

 certain would be highly dangerous as a source of treraatode in- 

 fection. 



More recently Annandale (1920 (6), p. 1) has noted that Pachylabra 

 (AmpuUariidae) is occasionally carnivorous. 



