SUB-ORDER B PLATYPODA 473 
posteriorly produced in a usually short canal. Outer lip inflected. Operculum wanting. 
Upper Jura to Recent. 
Recent Cypraeidae, of which about 210 species are known, inhabit principally the 
warmer seas. They are often remarkable for their beautiful coloration, and sometimes 
attain considerable size. Jurassic species are sparse; Tertiary ones rather more abundant. 
Cypraea, Linn. (Fig. 951). 
Ovoid, ventricose, enamelled, 
smooth, lirate, or tuberculate ; 
spire exposed or enveloped. 
Aperture narrow, extending the 
whole length of the shell, and 
canaliculate at each extremity. 
Inner lip and the inrolled outer 

lip generally crenulate. Jura Fig. 061. 
stone i +. 952 +. 953. 
(C. tutonrca, Stefani) to Recent. (ypraea subexcisa, Fic. 952. __ Fre. 953 
Trivia, Gray (Fig. 952), A. Braun. _ Oligo- Trivia afinis, Duj. Erato laevis, Don. 
Ore leStewes Gi cene ; Weinheim, sp. Miocene; Pont- Miocene ; Niederleis, 
Like the preceding, but smaller, pear Avey. levoy, Touraine. Austria. 
and sculptured with raised 
transverse riblets. Anterior channel not prolonged, wide and slightly reverted. 
Tertiary and Recent. 
Erato, Risso (Fig. 953). Small, ovoid or pyriform, with short conical spire. 
Aperture narrow. Inner lip smooth, except for anterior columellar folds; outer lip 
denticulate. Canal notch-like, broad. Cretaceous to Recent. 
Family 22. Ovulidae. 
Like the Cypracidae, except that the spire is convolute instead of produced and 
covered, and the marginal teeth 
of the radula are peculiarly 
modified. Tertiary and Recent. 
Ovula, Brug. Shell ovate 
or fusiform, the spire completely 
enveloped. Aperture produced 
anteriorly and posteriorly as a 
canal. Inner lip smooth; the 
outer inflected, smooth, or den- 
ticulated. Tertiary and Recent. 
Gisortia, Jousseaume (Fig. 
954). Large, thick - shelled, 
ovate, with -short convolute 
spire. Surface typically keeled 
or coarsely tuberculate. Body 
whorl with a blunt ridge; aper- 
ture anteriorly and posteriorly with a short canal. Eocene. G. (Strombus) gigantea, 
Goldf. sp. 
Pedicularia, Swainson. Miocene to Recent. 

Fic. 954. 
Gisortia tuberculosa, Duclos. Lower Eocene ; Cuise-la-Mothe. 
Family 28. Cassididae. Adams. 
Shell thick, inflated, globularly ovate, sometimes varicose ; spire short, body whorl 
very large. Aperture narrow, elongate, anteriorly with short canal. Inner lip resting on 
an extensive callus, sometimes granulated or wrinkled. Outer lip more or less thickened. 
Operculum horny, with marginal nucleus. Marine. Upper Cretaceous to Recent. 
