FOSSIL GASTROPODS. 249 
Various shells, such as Marginella, Turbinella, etc., are 
strung in bracelets and armlets by savages. Cyprea moneta, 
the cowry, is used for African money, and other shells are 
worked into various shapes for wampum or aboriginal money. 
On the other hand, an Olivella is used by the Californian 
Indians as money. Murex and Purpura afford the Tyrian 
dye. Allied to the latter is the whelk (Buccinum undatum). 
While a few Gastropods are pelagic, living upon the high 
seas, such as Janthina and the Nudibranch Glaucus, most 
of the species are submarine and live in all seas; the hardier, 
most widely diffused species living between tide-marks, the 
more delicate forms in deep water, ranging from low-water 
2. Sane 
Figs. 204-205.--The whelk; its tentacles and proboscis extended; a, egg-cap- 
sules; b, embryo shell. (Natural size.) 
mark to fifty or one hundred fathoms. The abyssal fauna at 
the depth of from 500 to about 2000 fathoms has a few char- 
acteristic mollusks, Many live on land and in fresh water. 
The largest, most highly colored shells live in the tropics, 
while those found in the temperate zones are less beautiful, 
and the arctic species are the smallest and dullest in color. 
The shells of the eastern coast of North America are 
divided into several assemblages, or faune, the West Indian 
or tropical shells, in some cases, reaching as far north as 
Cape Hatteras ; between this point and Cape Cod a north 
temperate assemblage occurs, and north of Cape Cod the 
molluscan fauna is essentially Arctic; many species being 
comnion to the arctic and subarctic seas of the circumpolar 
regions. 
