GENUS PYRAMIDELLA. 8 
this mollusk differs essentially from the animal of the Auricua, 
by the presence of the operculum, which we have just mention- 
ed, and by the situation of the pulmonary organ, which is a true 
branchia; nevertheless, in other respects, the characters of the 
shell have the greatest analogy with some specimens of this last 
family. 
Sowerby, in his Genera, proposes to bring back to the Py- 
RAMIDELLA, several species of shells, some of which are com- 
prised among the Auritcutm; I am not of the opinion of this 
author ; these species do not appear to me to unite the charac- 
ters observed in the genus which I have just described. As to 
the number of folds, which he supposes to vary, I have always 
found the same in all the specimens I have been able to examine ; 
and the folds upon the columella, being a distinctive character 
in this genus, it does not appear consistent to admit shells 
which are destitute of them. Besides, what appears to me un- 
answerably to establish an exact distinction between these differ- 
ent shells, those of the family PLICACEA are marine and oper- 
culated, while the others, on the contrary, live in fresh water, 
and are destitute of an operculum. 
The species of the genus PyramipELLa are not numerous. 
The shells are generally quite small, of an elegant form, elon- 
gated, marked with more or less deep spots. ‘The animals are 
very timid. No species has as yet been met with in our seas. 
They appéar to live in those of India, and upon the coasts of 
Africa. 
Le PYRAMIDELLA TEREBELLUM, Lam. The Gimlet Py- 
ramidella. 
(Collect. Mass. Lam.) Lisr., Conch., t. 844, fig. 72. 
Pl. I, fig. 2, et fig. 3 pointed. 
P. testa conico-turritd, umbilicata, levi, alba, lineis rufis cincta ; colu- 
mella recurva ; labro intus levigato. 
Shell conical, turreted, polished, elongated, slightly transpa- 
rent, white, beautifully adorned with transverse reddish or 
brown bands, three in number upon each whirl, and four or 
five upon the lowest, which is more inflated; the middle band 
