172 MARGINELLIDA. 
Distinguished by its Conus-like form, the columella with less 
numerous plaits than in most of the species of Cylindra; some 
species, like Cylindra dactylus, however, appear to connect these 
two forms. 
Famity MARGINELLID 2A. 
Shell porcellanous, polished, usually smooth or with longitu- 
dinal ribs; spire short or immersed, body-whorl ample, aper- 
ture nearly the length of the shell, the outer lip with usually 
thickened margin, smooth or dentated within, the inner lip with 
several distinct plaits on the columella. 
Animal with tentacles close together at the base, the eyes above 
the base or near the middle of the tentacles, mantle with expanded 
side-lobes covering the back of the shell as in Cyprzea; siphon 
elongate, foot large, truncate in front, produced behind. Oper- 
culum none. 
Dentition (x, 6). In possessing rhachidian pieces without 
laterals, the lingual armature of Marginella resembles that of 
Voluta, whilst the shape of the plate and its dentated edge are 
very similar to that of Mitridee—lateral teeth being added in the 
latter family. A single species of Erato (the only one examined) 
possesses three lateral teeth on each side like the Cypreide, and 
on this ground some systematists place Erato in that family. 
Marginella glabella sometimes possesses an operculum, but 
generally does not have it ; some of these operculate specimens 
also have a single lateral tooth on each side of the rhachidians 
on the lingual ribbon. Pseudomarginella, Carriere, is founded 
upon specimens possessing this very different dentition ; the shell 
does not differ at all from specimens of JZ. glabella in which the 
dentition is normal. 
The shell being covered by the mantle-lobes receives a polished 
surface and is devoid of epidermis, thus resembling externally the 
Cowries and Olives, whilst the plaits on the columella connect 
the family with Mitride. 

Erato, Risso. 
Distr.—17 sp. Europe, West Indies, So. Africa, Indian 
Ocean, Philippines, Polynesia, Tropical W. America. Fossil. 
Eocene— ; Europe. So. Australia, N. America. #. levis, Donov. 
(lv, 54). 
Shell obovate, polished; spire short, conical, distinct ; aper- 
ture linear; outer lip without varix, but thickened towards the 
middle, and denticulated within; columella with distinct plaits 
at the fore-part. 
ERATOPSIS, Hoernes and Auinger. Shell granular-tuberculate, 
with a longitudinal sulcus on the back of the body-whorl, as in 
Trivia. Includes five living species, and several forms from the 
Austrian tertiary. H. Schmeltziana, Crosse (lv, 55). - 
