Pulmonata 525 



sion concern unless they tend to get too far away from the water and 

 become too dry. 



The principle in the foregoing example is applicable to aquaria of all 

 sizes from finger bowls for snails kept individually to aquaria of 5 or 

 10 gallons capacity. 



MAINTENANCE 



Snails are fond of calcium carbonate in the form already mentioned 

 and most of it will have been collected and deposited in cylinders of 

 feces in a day or so. It is mixed subsequently with increasing amounts 

 of organic material, since the snails eat the feces repeatedly. The snails 

 should be given lettuce every other day and accumulation of excesses 

 should be prevented by regulating the amount given them. In case 

 excess lettuce remains, remove it at the subsequent feeding. Sometimes 

 an excess of lettuce is necessary to keep the snails in the water, and 

 in this event the portion remaining should be removed at each feeding. 

 The dry leaves should be removed and replaced by a fresh supply when 

 they become skeletonized. 



The water in the aquarium should remain clear and be colored only 

 slightly. Odors, cloudy conditions of water, and usually the crawling 

 of the snails out of the water are warning signs which indicate that some- 

 thing is wrong with the habitat. Cloudy conditions due to protozoans 

 are usually not serious; it is well in such cases, however, to reduce the 

 amount of green food for several days and to introduce a culture of 

 Cyclops into the aquarium. Cyclops are very desirable to have in any 

 aquarium intended primarily for snails, since they tend to keep down 

 excessive development of protozoans. Cloudy conditions of the water 

 due to causes other than those already mentioned should be watched 

 carefully; it is usually desirable to dispose of such abnormal appearing 

 aquaria although before so doing air may be introduced and allowed to 

 bubble through the water in an attempt to remedy the situation. In- 

 stead of cleaning such an aquarium and immediately using it again, it is 

 better to transfer the snails to a new container. Before introducing the 

 snails into the new habitat they should be rinsed and the shells wiped 

 with a dry cloth ; it may be necessary to repeat this procedure daily for 

 3 or 4 successive days in order to restore normal conditions. If an 

 abnormal condition cannot be corrected in this way it is possible that 

 the number of snails is too great for the size of the container. 



Most snails, apparently, thrive best in shallow water, not over 4 

 inches deep, although of the ones mentioned above Lymnaea palustris 

 and Stagnicola coper ata prefer 7 or 8 inches of water ; for snails requiring 

 the greater depth of water battery jars may be used for small aquaria. 



Some snails, such as Fossaria modicella, Helisoma antrosa, and Physa 



