MONOGRAPH OF THE GENUS STROPHIA. 
79 
OBSERVATIONS. 
As shown under Dimensions, there is great variation in size, in this 
species. This extreme difference has caused me considerable perplexity, 
for this seems to indicate much more than individual variation, and, in 
fact, rather more than varietal difference. These extremes represent 
two forms which show in the hundreds of specimens examined, but a 
small percentage of gradation. Then the smaller form is smoother and 
whiter, with the first three whirls nearly, equal in diameter; all are 
more bulging, and only 10 in number. These characters certainly show 
a strong tendency toward assuming specific rank, and with complete 
isolation from the larger form, would soon become fixed enough to war- 
rant a name, but as the shells inhabit a very limited area, 1 leave them 
as they are for the present, under the name of S. incana. 
Mr. W. C. Binnev in “Land and Fresh Water Shells of N. A.,” 
page 247, says that he has seen a variety of S. incana with longitudinal 
markings; in this, however, I cannot well avoid thinking him mistaken, 
some other species evidently being indicated. In his quotation of local- 
ity of specimens, he gives Key Biscayne, Fla., and from this island he 
may have got his colored specimens. As this latter named place is 
over 100 miles, in a direct line, from Key West, with numerous water 
ways through which the tides sweep with great force, between, this dis- 
tance would afford more than sufficient isolation for the evolution of a 
distinct species, even if the original stock w T ere S. incana. This seems 
to be a matter th?t requires special investigation, and for further re- 
marks upon this subject see under head of Observations in forthcoming 
species. 
Known from all other species, by the absence of striations, white 
color, with the very pale interior, small size, thin shell, and short teeth, 
DISTRIBUTION AND HABITS. 
The Gray Strophias occur in a limited area, on the island of Key 
West, Florida. According to my experience they are restricted to that 
portion of the northern side of the key that lies between the salt ponds 
and the Gulf of Mexico. In habit they are somewhat peculiar, as many 
hvbernate beneath stones, and as spring advances, emerge to feed upon 
the short herbage that grows rather scatteringly in the section in which 
they live. 
This species is said to occur in Cuba also, but I have never seen 
a specimen from that island, nor have I ever met with it on other of 
the Florida Keys. 
