292 PROCEEDrXGS OF THE NATIONAL }IUSEVM. vol.xxiv. 
The late Dr. James Lewis "attributed malleation to rapid growth 
in warm water, causing the shell to solidify unevenly. He also men- 
tioned apparent metamorphoses of one species into another quite dif- 
ferent, merely from change out of still canal water to that of a rapid 
brook. " 
Neither Dr. Lewis's hypothesis nor Call's Lltnnmi honnevillensis 
and the same author's variety utahensis of Z. ampl<(, the latter occur- 
ing' in an environment wherein salinity is a factor, are of much value 
as bearing on the phenomena of sculpture in these and related forms 
in the fa(;e of the Eagle Lake shells before referred to and Lea's 
PhyKCi carlton! from near Antioch, at the junction of the San Joaquin 
and Sacramento rivers in California. 
SCULPTURE AND THERMAL WATERS. 
Phym frequently occurs in thei'mal springs or waters far above 
their ordinary summer temperature. Dr. Lea's P. aurea from Hot 
Springs, in Bath County, Va., included by Binney as a synonym of 
P. heteroxtrojjha^ is an instance in point. Here waters of different 
temperatures come together forming a little stream — on one side of 
106'-', the other, 56°. Dr. Lea made no note of sculptural differences. 
Numerous examples of another form from a hot spring in Alameda 
County, California, examined b}^ me, showed only fine growth lines. 
Dr. Merriam's specimens of P. gyrina from Hot Springs, Panamint 
Valley, California, "fine, large, dark-colored shells," exhibited no 
special sculptural features, and the same may be said of Bailey's 
examples of P. heterostropha from the same region. From the above 
we may conclude that sculptural character is not affected or developed 
by the thermal factor in springs, etc. , and this is still further supported 
by the desert shells, which, outside of the hot springs, were subjected to 
the sun-heated waters of the shallow pools during the long and exces- 
sively hot summers of the desert region. 
Incidentally, mention may here be made that the shells of PJiysa 
from thermal stations are noticeable for their fine texture, shining 
surface, and clear dark or light amber color. 
SIZE AS RELATED TO HYPSOMETRIC TEMPERATURES. 
"Hypsometric distribution has received from conchologists," as 
Dr. Call has said, "much less attention than it apparently deserves. 
Within small areas, comparatively, there are presented by hypsometry 
those various physical conditions that must otherwise be sought 
through several degrees of latitude." 
So it may be said that the paths of distribution of various living 
forms are along the lines of temperature, measurably, wherever such 
lines may lead, which may explain the southing of many so-called 
Northern species and the northing of so-called Southern forms, with 
