174 OLIVIDA. 
Cyprea. The dorsal aspect is much like Cyprea. MM. sarda, 
Kiener (lv, 63). 
voLtvARIA, Lam. (Hyalina, Schum.) Shell subcylindrical, 
spire very short or concealed; outer lip of aperture without 
varix or thickening. MM. avena, Gmel. (lv, 64). UM. bulloides, 
Lam. (lv, 65). 
Famity OLIVID&. 
Animal with a recurved siphon and voluminous foot, its lobes 
usually reflexed over the sides of the shell, and fissured on each 
side in front. Dentition (x, 15). 
Operculum corneous, small; frequently wanting. 
Shell brilliantly colored, porcellanous, without epidermis, the 
columellar lip, sutures and spire more or less Govered with a 
callous deposit; outer lip simple, notched below. 
Suspramity OLIVINA. 
Head and tentacles more or less concealed; mantle with a 
tapering lobe in front, and a posterior appendage which reposes 
in the channeled suture. 
Operculum present in Olivella, absent in the typical Oliva. 
Shell solid, smooth, subcylindrical, sutures channeled, inner 
lip more or less plicate anteriorly. 
OLIVELLA, Swainson. 
Rice-shell. Syn.—Olivina, d’Orb. Micana, Gray. 
Distr.—31.sp.. N. Carolina, W. Indies, W. Coast of America, 
Senegal, China, Philippines, Australia, Polynesia. O. undatella, 
Lam. (lvi, 66). 
Shell polished, small; spire produced, acute, suture canalicu- 
lated; aperture narrow behind, enlarged anteriorly ; columella 
plicated in front, callous posteriorly. 
Animal without tentacles or eyes, mantle with a large frontal 
lobe; foot not very voluminous, truncate behind, the shield 
narrow, the side-lobes small and acute. 
Operculum horny, thin, half ovate, with apical nucleus, 
Olivella is distinguished from Oliva by the small size of its 
shell, its more produced spire, the presence of a large, thin, 
horny operculum, and the want of eyes. D’Orbigny has observed 
O. Tehuelcha suddenly expand the lobes of its foot, and using 
them to beat the water like the wings of the pteropods, dart 
rapidly through the element. 
Oriva, Brug. 
_ Syn.—Dactylidia, H. and A. Ad. Ispidula, Gray. Porphyria, 
Bolten. Strephona, Browne. Dactylus, Klein. Galeola and Car- 
mione, Gray. sgaateh 
