283 TRACHELIPODA. CALPURNA. 
expanded, and notched; columella smooth, truncated at the 
base. 
Section 1. — Spire visible. 
Terebellum fusiforme, Plate III. fig. 15. Fossil, in the 
London Clay. 
Section 2. — Spire invisible, or slightly apparent. 
Terebellum convolutum. Plate III. figs. 16, 17. 
Montfort considered the concealed spire sufficient reason for forming a sepa- 
rate genus of this last species, under the name of Seraphs ; but it appears to be 
only in the adult state that it assumes this character, because, if broken, the 
spiral canal is distinctly visible. 
The shells of this genus inhabit the Indian Ocean, of which one recent species 
only is known. 
Genus V.— CYPRZA. — Linneus. 
Generic Character. — Shell strong, particularly in front, 
ovate, or oblong-ovate, convex behind, and somewhat flat- 
tened in front; margins involute; spire very small, gene- 
rally hidden by the upper portion of the last volution, which 
is rolled around the under volutions, as if around a longi- 
tudinal axis, and invested by a coating of enamel in the 
perfect or adult condition; the whole surface usually 
beautifully polished, and for the most part ornamented by 
spots, eyes, or zigzag markings; some few are grooved or 
ribbed on the external surface, and these have but little 
polish ; aperture long, narrow, extending nearly the whole 
length of the shell, dentate on either side, effuse at the ex- 
tremities ; outer lip thickened and inflected. 
Cyprea avellana, Plate IV. fig. 21. 
Found in the London Clay. The species are pretty numerous in a fossil 
state, in the newer formations; they occur in the Crag, and in the Calcaire- 
grossier of Paris, Normandy, and Laugnan near Bordeaux. 
The Cyprzid# undergo considerable change of aspect in their progress from 
the young to the adult state, and in their unfinished condition, may be mis- 
taken for species of Bulle and Ovule. They are oceanic shells, inhabiting the 
seas of the warmer portions of the globe, one species only being found in 
Europe. 
Genus VI.— CALPURNA. — Montfort. 
Generic Character. — Shell oblong, oviform, somewhat 
attenuated at both extremities with abbreviated canals ; 
aperture longitudinal ; outer lip smooth and thickened ; 
columella with a notch at its base. 
