260 CLASS III]. GASTEROPODA. ORDER VII. PECTINIBRANCHIATA. 
the system. He may delight in the identification of species, but should 
be careful to examine their relative affinities, and not be satisfied with the 
mere discovery of a difference in kind. By adopting the genus Erato we 
are brought to consider the relation between two apparently remote fami- 
lies, and at once discover an affinity between parts which before it seemed 
difficult to associate. 
The shell of Erato may be described as being small, ovately-oblong, 
smooth, and emarginated at the base, the spire being rather prominent, 
and the last whorl somewhat inflated ; the aperture is narrow, and both 
the columella and outer lip are denticulated, in some instances throughout 
their entire length ; the margin of the latter is thickened, swollen towards 
the middle, and rounded at the upper part. 
Examples. 
Pl. CCLXXXV. Fig. 1. 
Erato aNneistoma, Sowerby, Catalogue of Cypreade, p. 16. No. 7. 
Conchological Illustrations, f. 51. 
Pl. CCLXXXV. Fig. 2. 
Eravo sutcirera, Gray. Sowerby, Catalogue of Cypraade, p. 15. No. 2. 
Conchological Illustrations, f. 46. 
Pl. CCLXXXV. Fig. 3. 
Erato tavis, Gray. Sowerby, Catalogue of Cypreade, p. 15. No. 3. 
Conchological Illustrations, f. 57. 
Cyprea Voluta, Montague. 
Voluta levis, Donovan. 
Marginella Donovani, Payrandeau. 
Pl. CCLXXXV. Fig. 4. 
Erato Mauceria, Gray. Sowerby, Catalogue of Cypraadz, p.15. No. 4. 
Conchological Illustrations, f. 47. 
