MOLLUSCA.—CLASS IV. PTEROPODA. 279 
CUVIERIA, Rang. 
° 
Testa tenuissima, alba, aut cylindrica, aut globulosa, aut hemispherica ; 
posticé rotundata, obtusa, truncata; anticé depressa, pervia, aper- 
tura transversali, partim obliqua. 
Three other genera were proposed by Rang in his ‘ Manuel de Conchy- 
hologie’ for the subdivision of the Pteropods: Cuvieria for such as have 
a cylindrical sheil ; Psyche for those in which it is globular ; and Eurybia 
for those whose shells assume a hemispherical form. These three varia- 
tions of form approximate, however, so closely, and run so completely 
into each other, that we do not hesitate to unite them under the first of 
these titles. 
The shell of Cuvieria may be described then as being very thin, white, 
and either cylindrical, globular, or hemispherical; the posterior end is 
rounded, obtuse, and truncated; the anterior depressed, and open, the 
aperture being transverse, and slightly oblique. 
Example. 
Pl. CCXCV. Fig. 6. 
CuviERIA COLUMNELLA, Rang, Manuel de Conchyliologie, pl. 2. f. 4. 
D’Orbigny, Voyage dans l’Amérique Méridionale, Mollusques, pl. 8. 
f. 35 to 39. 
Cleodora columnella, Deshayes. 
CYMBULIA, Péron. 
Testa gelatinoso-cartilaginea, crystallina, oblonga, calceoliformis ; posticé 
truncata ; anticé pervia, apertura sublaterall. 
This Pteropod was discovered by Péron, and differs essentially from 
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