yew YORK SHELL CLUB NO 2 January 1978 Page 5 
tand shells can be even harder to find, but in shad 
moist (but not wet) shelters such as fallen tree i Room fone 
corrugated boxes, leaves, paper and bits of wood, and in talus 
slopes they may be found in satisfactory numbers. The largest are 
the White-lipped Forest Snail (Triodopsis albolabris) and its rela- 
tive, the Common White-lipped gaat Tathecades aueria yroidus). Almost as 
large and much more colorful are the Striped Fores nails (Trio- 
dopsis tridentata). A rare snail, covered in life with a hairy epi- 
dermis, 1S the very interesting Hirsute Forest Snail (Triodopsis 
denotata). Although we have as yet no records of the ree ger 
the Palisades area, it is likely that the colorful English Garden 
Snail, (Cepaea nemoralis), a recent introduction, will be found in 
ardens and in compost heaps. Other, larger snails are the various 
forms of the glistening snails (Oxychilus sp. and Mesomphix sp.), 
the Pill Snails (Stenotrema sp.), the Cannibal Snail (Haplotrema 
concavum) (so called because it is a predator on other saatier weien 
are largely plant and fungus eaters), and the Amber Snails (Succinea 
sp.). There are in addition large numbers of small to tiny snails 
like the flattened Zonites (Zonitoides sp.) and Disk Snails (Discus 
sp.), the elongated but truly tiny Pupa Snails (Gastrocopta, Vertigo, 
Columella etc.) and the small but handsome Apple Seed snail (Ci aaohT A 
Iubrica). Mention should also be made of Vallonia, and the tiniest 
of all land snails, the Tiny Mulch Snail (Punctum minutissimum). To 
complete the roster, we add the following: Hawaiia minuscula, Reti- 
nomen ene 
nella, Euconulus sp. (the Beehive Snails, so-called because they re- 
semble a tiny, old-fashioned beehive) and Strobilops sp., the Laby- 
rinth Snail, which gets its popular name from a number of small 
ridges inside the aperture that look like a very simple maze or 
labyrinth. 
Most of the above-mentioned species are described and illustrated in 
a handbook, SHELLS from CAPE COD to CAPE MAY, by Morris K. Jacobson 
and William K. Emerson, 1971, Dover Publications, Inc., New York. 

ONE PART PER MILLION 
I am frequently asked what one part per million of anything looks 
like, or can be visualized as, so that people can understand what 
the environmentalists are talking about. Here's how I go about try- 
ing to make it plain: 
Imagine a cube 25 feet on each s 
24 stories high), then imagine i 
Clean clear water such as one can 
ide (or a building 25 feet square, 
t full of seawater, preferably nice, 
find in the Caribbean. Now imag- 
ine you dump in just one pound of your favorite pollutant. That's 
it! You how 8 one part per million. A cube that size has 15,625 
cubic feet, and seawater weighs 64 pounds per cubic foot. 
Just for kicks, measure the meeting room for cubic volume, and see 
ow many would care to be there if it were full of seawater plus one 
Pound of some sort of poison. 
t hope this brings home to our members what one of the more common 
erm i eans. 
S used by environmentalists m stein aay 
An item i ine the danger of minute percentages of pollution 
was Peiicd in HE MOLLUSK of the Greater Miami Shell Club, Novem- 
ber, 1977, 15(11):10, which was reprinted from THE MIAMT HERALD of 
