FAMILY 12. CONVOLUTA. 2 
On 
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ERATO, Risso. 
Testa parva, ovato-oblonga, levis, ad basin emarginata, spira subpro- 
minula, anfractu ultimo subinflato ; apertura angusta, columella la- 
broque interdum per totam longitudinem denticulatis ; margine 
externo incrassato, mediané tumido, superné rotundato. 
We are indebted to M. Risso, a distinguished conchologist of Nice, for 
the introduction of this important genus ; important, because serving to 
establish a close affinity between two apparently very different genera. 
The genus Erato was proposed by that author for the sake of distinguish- 
ing a small shell from the Mediterranean, exactly intermediate in its cha- 
racters between that of Marginella and Cyprea; but it may be distin- 
guished from either on examination. Instead of the columella being 
plaited in all its several stages of growth, as in the former, it remains 
perfectly smooth until the shell arrives at maturity ; the columella, to- 
gether with the outer lip, then exhibit a number of fine denticulations, 
as in the Cypre@, whilst the shell, with its rather elevated spire, retains 
the form and general appearance of the Marginelle. It must, however, be 
remarked, that the peculiarity of character attached to the columella of 
this shell presents a considerable degree of modification in different spe- 
cies. Of the seven represented in our Plate, the columella in some almost 
assumes a plaited appearance ; they may, nevertheless, be readily distin- 
guished, and it is to be regretted that Kiener should have followed Pay- 
randeau in confounding them with the Marginelle. They form a well- 
marked and very decided link between the two families of the Colwmel- 
lata and the Convoluta, and certainly merit a generic notice, if only on 
that account. 
A genus may be considered important if aiding to establish a connec- 
tion between two seemingly distinct families, when it might otherwise be 
set down as frivolous and unnecessary ; for the naturalist should labour 
diligently to display the harmony that exists between the several parts of 
