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CHAPTER VII
Periwinkles
Conchs and Other Snails
Class GASTROPODA
Subclass PROSOBRANCHIA Order ARCHAEOGASTROPODA
Superjamily PLEUROTOMARIACEA
Family SCISSURELLIDAE
Genus Scissurella Orbigny 1823
Subgenus Schizotrochus Monterosato 1884
Scissurella crispata Fleming Crispate Slit-shell
Massachusetts to eastern Florida and the West Indies. Europe.
3.5 mm. (Vs inch) in width and 3.0 mm. in length. 4 to 5 whorls. Fragile,
frosty-white in color and sculptured by very delicate reticulations. Umbihcus
small, round and very deep. Periphery of whorls angulate and with two
thin, sharp spiral lamellae. Between these there is an open
slit running from the edge of the thin apertural lip back
about % of a whorl. Uncommon from 60 to 500 fathoms.
The Florida Slit-shell, 5. proxivm Dall (fig. 29), from
South Carolina to the Lower Florida Keys, differs in being
half as large, with a more rounded periphery, and a higher
spire, so that the length is about equal to the width of the
shell, and in having a weaker pair of peripheral lamellae.
Uncommon from 20 to 434 fathoms.
Fajnily PLEUROTOMARIIDAE
Genus Perotrochus P. Fischer 1885
Perotrochus quoy anus Fischer and Bernardi
Quoy's Pleurotomaria
91
Figure 29.
Florida Slit-
shell, Scissurella
proxi?77a Dall,
YiQ inch (Massachusetts
to Flor-
ida, 20 to 430
fathoms).