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ZOOLOGICAL SOCIETY BULLETIN 



hermaphroditic, both sexes being present in each 

 individual, but the eggs are cross-fertilized. 

 The eggs number from seventy to one hundred, 

 according to the species, are laid in horse-shoe 

 shaped masses of gelatin attached to plants or 

 to the sides of the aquarium, and hatch in two or 

 three weeks. 



The ramshorn shells are of a very ancient 

 type, being found in fossil remains of great an- 

 tiquity. They are of numerous species, the com- 

 monest being the brown Planorbis, a clumsy 

 snail measuring scarcely more than half an inch 

 in diameter. It lays about eighteen yellow eggs 

 in gelatin and does well with little fishes such 

 as shiners, banded minnows and dace. It often 

 carries on its back a menagerie as well as a roof 

 garden, colonies of protozoa and rotifers, water 

 bears and other minute animals. Specimens are 

 said to have become active after being without 

 water for four months. 



There is a ramshorn shell (Planorbis magni- 

 ficus) indigenous to certain streams of North 

 Carolina, that is the giant of its type in this 

 country, some specimens measuring one and 

 three-eighths inches in diameter. It is called 

 the Cape Fear River Snail. It has been ob- 

 served chiefly for scientific data, has eyes when 

 young which later degenerate and. becoming 

 covered with cuticle, render the adult sightless. 

 It is probable that the rarity of this large shell 

 will prohibit its general introduction into home 

 aquaria, although, as its name indicates, it is 

 a magnificent snail. 



The European Red Ramshorn ( Planorbis 

 coniciis rubra) originally introduced from Ger- 

 many and numbers of which are now bred in 

 America, is the ramshorn shell most commonly 

 used in home aquaria ; a handsome, active snail 

 an inch and a quarter in diameter, ruby bodied 

 and ruby-shelled when young, the shell becom- 

 ing striated with brown and black as its size in- 

 creases. It is also called Copenhagen, Coral, 

 and Red Post Horn Snail, and occasionally 

 Trumpet Snail. It breathes by means of a lung, 

 often visiting the surface for air, and manages 

 its shell more dexterously and gracefully than 

 the American Planorbis, never giving the im- 

 pression that it labors under an embarrassing 

 weight. This is partly due to the advantage 

 of having a longer body to control both the foot 

 and the shell. Like most pulmonate shells 

 (lung breathers) it is hermaphroditic and cross- 

 fertilization takes place. The pink eggs, num- 

 bering from ten to forty-five, are enclosed in an 

 ovate mass of gelatin attached to the stems of 

 plants. 



The eyes and the siphon (which is at the side 

 of the shell, behind the body) are enormous in 

 newly hatched specimens, and the shell at birth 

 is thimble-shaped and shows no convolutions, 

 the color being dirt}- yellow with faint touches 

 of pink. The baby snail just out of the egg is 

 barely visible to the naked eye, but begins ac- 

 tivities at once, and can travel an inch in five 

 minutes. 



The eggs are preyed upon by microscopic ani- 

 mals of various sorts, but given a clean aqua- 

 rium, a little lettuce and scraps of meat or fish, 

 with chalk, gypsum, ground coral, plaster of 

 paris or cuttlefish to provide lime for the grow- 

 ing shells, and the red snail will breed rapidly. 

 It is desirable to place only full grown speci- 

 mens with fish, the younger ones being likely 

 to fall prey to their finny companions. The red 

 color is, speaking eugenically, a recessive trait, 

 and is lost if the snail is bred with our native, 

 sombre-hued ramshorns. 



The Potomac Snail ( Viviparus viviparus, 

 formerly Paludina) and the Japanese Snail 

 {Viviparus malleatus) have the fault of becom- 

 ing somewhat dormant in the winter, moving 

 about only on the milder days or when the sun 

 is upon them. The Potomac Snail, whose shell 

 measures an inch and a half in length, is gen- 

 erally more sluggish than the larger Japanese 

 variety, which is over two inches long. This 

 sluggishness is so dominant a quality that those 

 who have interbred them record the resulting 

 progeny as sluggish and short-lived as the Po- 

 tomac Snail. The males of both species have 

 one tentacle shorter than the other, while those 

 of the female are of even length. 



Both the Potomac and Japanese Snails are 

 ovoviviparous, the eggs being retained within 

 the mother's shell till they hatch. The young 

 shells are hard enough at birth to protect them 

 from small aquarium fishes. It is believed that 

 the female of the Japanese snail after once mat- 

 ing, remains fertile the remainder of her life. 

 Both species have remarkably small appetites, 

 yet help to clarify the aquarium, and are of an 

 ideal size to be kept with goldfish. They are 

 gill breathers, not needing to rise to the surface 

 for air. and have a horny operculum for the 

 complete closure of the shell. 



The dark brown shell of the Japanese Snail 

 often presents a fuzzy green aspect, because of 

 the dense growth of minute plants with which 

 it is overgrown. 



The only fertile specimen the present writer 

 has observed, produced fourteen young in seven 

 days and then rested. At birth the Japanese 



