ZOOLOGICAL SOCIETY BULLETIN 59 
FRESH-WATER LIMPET, ANCYLUS 
Smallest of fresh-water snails. 
Drawn by Ida M. Mellen 
food of fishes, and if the shells are too large to 
tackle, the fishes will nibble off the tentacles 
and kill the snails. 
Potomac snails are short-lived in captivity, 
and the most desirable of all aquarium snails is 
the Japanese, commonly sold in bird and animal 
stores. Once fertilized the female is said to be 
fertile for life and reproduces at odd times dur- 
ing the year. One owned by the writer pro- 
duced fifty-four young in a year, and when she 
died, thirteen young were cut out of the mantle 
and placed in a tumbler of water. In a few 
hours twelve were climbing up the side of the 
tumbler and continued to thrive. These young 
snails began to breed when three years old, but 
at four years are not yet half the adult size, 
though it is hardly to be supposed that their 
growth.is so slow in a state of nature, but rather 
that, like fishes, with a limited space to live 
in, they tend to become dwarfed. 
The Japanese snail has a remarkably small 
appetite and does not damage the plants. It re- 
fuses to eat lettuce, of which all soft-shelled 
snails are so fond. It eats the fine algae that 
forms on plants and glass, and seems to prefer 
prepared fish foods to fish and meat, though it 
will on occasion consume the latter. It must 
be provided with shell-making substances, such 
as powdered cuttlefish or plaster of paris; other- 
wise the shell becomes perforated and death en- 
sues. The Japanese snail, being provided with 
a strong operculum, completely closes the shell 
with it and may go to sleep for a week at a time. 
Relaxation of the muscles is the first evidence of 
death, and if a snail, lying with the operculum 
open, does not contract when touched, it is time 
to remove it from the aquarium. The sexes are 
easily distinguished when the snail is crawling. 
The male carries his right tentacle curled, 
whereas the female carries both her tentacles 
straight. 
THE GOLDFISH 
Animals that are produced by artificial selec- 
tion tend to revert to type; and with all their 
fantastic shapes and glorious colors, goldfishes, 
so far as we know, are descended from plain 
blue-brown carps (though some aver from the 
yellow crucian carp), just as faney pigeons are 
descendants of the modest gray rock pigeons, 
and domestic fowls descendants of the jungle 
fowls of India. 
If man’s continuous artificial selection is re- 
moved, goldfishes finally return to type just as 
pigeons and fowls do, and those who would 
breed fancy types must weed out all but the 
best, in the same manner that Burbank weeds 
out all but the best of his artificially produced 
varieties of plants and trees. Only strict elimi- 
nation of the young that fail to resemble their 
parents in all expected points, will keep the 
type true. 
Fishes lay a great many eggs, just as plants 
produce many seeds, and breeders can attord to 
be ruthless, though of course specimens not 
strictly true to type are as satisfying as any 
to a beginner, who does not care about possess- 
ing valuable breeds. 
SPAWNING 
Goldfishes begin to breed when in their sec- 
ond year, and continue six or seven years, being 
at their best when from three to five years old. 
Young males are considered more fertile than 
older ones, and two or three are generally al- 
lowed to fertilize the eggs of one female. The 
sexes are readily distinguished in the breeding 
season, the male by his little white tubercles 
dotting the gill covers and pectoral fins like 
decorative beading, the female by her enlarged 
dimensions when swollen with eggs. 
All fishes should have richer foods during the 
spawning season. 
A general belief prevails among aquarists 
that fishes become roebound and will die unless 
relieved; but specimens that appeared to us at 
the Aquarium to have died from being roebound, 
proved, on examination, to have parasitic or 
other troubles from which death might quite as 
readily have ensued. If it appears that a choice 
specimen is going to die anyway, there may be 
some satisfaction in having at least tried to strip 
it. This may be accomplished by placing the 
thumb in front of the vent and exerting pres- 
sure toward the tail, until the eggs are pressed 
out. Sometimes goldfishes have been treated in 
this way merely until the oviduct protruded. 
wv & od 
POTOMAC SNAILS AND NEW-BORN YOUNG 
American counterparts of the Japanese black snail. 
