MOLLUSCS, VERMES AND HYDROZOA 



They are for sale in the Oriental quarters of some of the Pacific 

 cities, and are collected in the rice fields near Yokahama and there sold 

 for a few cents a quart. They are ovo viviparous, very hardy, most tenacious 

 of life, and when not buried under the pebbles, the most indefatiguous 

 "workers" of any of the snails bred as aquarium scavengers. In the 

 author's vicinity they may be had of several breeders who have given them 

 preference to the other three desirable species. The shell is similar to 

 V. viviparus but darker in color, lacking the bright color bands, and has 

 a distinct keel in the centre of the body whorl, extending part-way on the 

 next following. They grow to a diameter of 2 inches and over, and their 

 almost entirely black color makes them conspicuous inhabitants of the 

 aquarium. They are harmless to the plants, ravenous feeders on algse and 

 offal, never at rest and constantly moving over the glass of the aquarium, 

 or feeding on the parasitic algse on the water plants and on the humus under 

 the pebbles. The young, when they leave the female, are ^ inch in 

 diameter, having a horn-colored, very markedly keeled shell. The Chinese 

 species of the same genus' is F. stelmaphora, for which the above has been 

 mistaken;, but this snail has not been introduced into the United States. 

 The Japanese snail will cross with the Potomac snail, the mixed breed 

 more resembling the latter, as it does not have the keeled shell of the 

 Japanese snail. 



For the aquarium intended and equipped for fishes, these four species 

 are particularly recommended. Nearly all the others mentioned are not 

 desirable and should be introduced only when the approved species 

 cannot be obtained. More than one species is also advisable, as they all 

 vary somewhat in their preference of diet. 



Snail Breeding. A "snail farm" in which the desirable aquarium 

 snails may be bred is best arranged in a large jar in which there is a 

 luxuriant growth of aquatic plants rooted in clean soil and covered with a 

 thin layer of sand. No fishes or insects should be introduced, as they prey 

 upon the young snails when first liberated from the gelatinous capsules of the 

 oviparous species and the newly born young of the ovoviviparous genera. 

 Feeding with any of the starchy fish foods should be occasionally done, as 

 the young snails thrive better than when entirely dependent upon algae 

 and decaying vegetation; but this should not be done in excess that the 

 snails may not feed too considerably upon this supply and thereafter become 

 less effectual scavengers. Excessive feeding would also contaminate the 

 water and cause the death of the snails. 



When many snails are kept in an aquarium, it is advisable to place a 

 few pieces of gypsum or of plaster of paris, about the size of a large pea, in 

 the tank three or four times a year. These gradually dissolve and 



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