THE - CONCHOLOGISTS’ +: EXCHANGE 
THE STRENGTH OF SNAILS 
ERCEIVING a common snail, //e/ix aspersa, 
crawling up the window blind one eve- 
ning, it occurred to me to try what it could 
draw up perpendicularly. Accordingly, I at- 
tached to its shell four reels of cotton, fasten- 
ing one after the other until T ascertained that 
a greater load would exceed the limit of its 
strength. I then weighed the entire load and 
found that it weighed 214 ounces while the 
snail weighed only 14 ounce. ‘Thus it was 
able to lift perpendicularly nine times its 
weight. I then made an experiment with a 
larger snail weighing one-third ounce, the load 
being composed chiefly of the same material 
as the last but so placed as to be drawn in a 
horizontal position on the table. Reels of 
cotton to the number ot twelve were fastened 
to it, with a pair of scissors, a screw driver, a 
key and a knife, weighing altogether seven- 
teen ounces, or fifty times the weight of the 
snail. The same snail when placed on the 
ceiling was able to travel with a weight of 
four ounces suspended from its shell. I next 
tried it on a piece of common thread suspended 
and hanging loose with another snail of its 
own weight which it carried up the thread 
with apparent ease. After this I tried it on a 
single horse hair strained in a horizontal posi- 
tion, but it had then enough to do to crawl 
over this narrow bridge without a load. [E. 
Sandford, The Gardens, Dale Park, Arundel, 
Eng. in Zoologist for December. ] 
RARE CYPRAAS 
T will be of interest to our readers to have 
before them a list of the rarer Cypreas, 
partial it is true, but still valuable to col- 
lectors of this beautiful and interesting genus. 
CYPRAA 
aurantia, Min 
Barclayi, Reeve 
bicallosa, Gray 
Bregertana, Crosse 
Broderipii, Gray 
candida, Pease 
castanea, Higgins 
chrysalis, Kiener 
chrysostoma, Kiener 
clara, Gaskoin 
coffea, Gray 
compla, Pease 
contaminatla, Gray 
Crosset, Marie 
Jusco-maculata, Pease 
gemmula, Weinkauff 
Goodalit, Gray 
gracilis, Gaskoin 
guttata, Rumphius 
helene, Roberts 
Jenningsiana, Perry 
lentiginosa, Gray 
leucodon, Broderip 
leucostoma, Gray 
marginata, Gaskoin 
Menkena, Deshayes 
notata, Gill 
pardalina, Dunker 
parvula, Philippi 
Peasel, Gaskoin 
petitiana, Crosse and Fisher 
pulchella, Swainson 
LReevet, Gray 
Sauliea, Gaskotin 
Semiplota, Mighels 
testudinaria, Linneus 
umbilicata, Sowerby 
valentia, Perry 
EROSION OF FRESH-WATER 
SHELLS 
R. George W. Shrubsole ( Journal of 
Conchology, V, 66, 1886) has some 
notes on erosion of fresh-water shells. 
He noticed that in specimens of Planorbts 
living in the Trent Canal, the shell was entire, 
but after being kept for three months in water 
from the River Dee, considerable erosion had 
taken place. This suggested that the char- 
acter of the water might have a prominent 
place in the erosion, and analysis showed that 
the water of the Trent Canal contained about 
three times as much lime in solution as that 
from the River Dee. The fact that erosion 
did not set in at’once is explained by the exist- 
ence of the epidermis.—American Naturalist 
for December, 1886. 
