FAMILY 10. PURPURIFERA. 211 
The Strombus oniscus of Linneeus, which Lamarck included with the 
Cassidarie, was selected by Sowerby as a type for the formation of this 
genus, and we only regret that it has not been appreciated by conti- 
nental writers. The Onisciz have a much more solid and compact shell 
than the Cassidarie, the canal is scarcely recurved, and the columellar 
lip is particularly characteristic in being widely spread over the body 
whorl, with the surface curiously granulated. Deshayes rejects this 
genus because we are as yet unacquainted with the animal, and therefore 
unable to determine the strict propriety of its introduction ; but may we 
not infer that these granular spots or excrescences, which are very dif- 
ferently disposed from those which the shells of the Cassides sometimes 
exhibit, indicate a sufficient variation ? 
The shell of Oniscia may be described as being of an oblong or some- 
what cylindrical form, ending with a short, and nearly straight canal ; the 
spire is also rather short, and generally obtuse at the apex; the aperture 
is narrow, and longitudinal ; the columellar lip spreads widely over the 
body whorl, and is profusely covered with small granular pimples; the 
outer lip is irregularly denticulated, and somewhat contracted towards 
the middle. 
Examples. 
Pl. CCLIIE. Fig. 1. 
Oniscia Strromsirormis, Nobis, Proceedings Zool. Soc., 1842. 
Pl. CCLIII. Fig. 2 to 4. 
Oniscia TUBERCULOSA, Sowerby, Genera of Shells, Oniscia, p. 2. 
Pl. CCLIII. Fig. 5 and 6. 
Oniscra Dennisoni*, Nobis, Proceedings Zool. Soc., 1842. 
* This valuable shell, the vivid colour and beauty of which is not in the least exaggerated 
in our representation of it, is so nearly allied to the Oniscia cancellata, that we were disposed 
at first sight to question the propriety of separating it. A minute examination, however, 
assured us that it differs essentially in many respects; the whorls are evidently more angu- 
lar, the spire more depressed, and just within the outer lip is a row of blunted tubercles ; 
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