PROSOBRANCHIATA. 159 
No. 97. VoLuTa TRICORONA. Sowerby. Tab. XX, figs. 7 a—d. 
VoLura TRICORONA. Sow. 1843. Min. Con., vol. vii, p. 6; t. 613, fig. 2. 
V”. testé ovato-rhomboidali, costatd, transversim sulcatd, antice profunde emarginata ; 
spird brevi, apice acuto ; anfractibus obtuseangulatis, triplict serie spinarum nodiformium coro- 
natis ; costis numerosis, angustis, fere ad basin tendentibus ; sulcis transversis erregularibus, 
Lineis incrementi decussatis : apertura elongato-ovdli, postice subcanaliculata ; labro simplici, 
levi ; labio effuso ; columella biplicaté. 
Shell rhomboidal-ovate, longitudinally ribbed, transversely furrowed ; spire short, 
apex small, pointed: whorls bluntly angulated at the shoulder; ribs rather numerous, 
narrow, extending almost to the base, and surmounted by three rows of short nodiform 
spines; furrows rounded, shallow, crowded and irregular on the posterior part of the 
whorl, déep, distant, and regular towards the base; decussated by thick conspicuous 
lines of growth: aperture of a lengthened ovate shape, deeply notched in front, and 
terminating behind in a short, wide canal; outer lip thin, smooth within ; columella 
nearly straight, flattened on the anterior surface, and furnished with two folds, of which 
the front one is thick and very oblique. Only imperfect traces of the inner lip remain 
in the specimens I have seen, but it was apparently widely spread, covering the front 
of the body whorl, and stretching backwards far up the spire. 
This Volute, which appears to be peculiar to the lower formations, is very rare. 
In the general form it resembles V. denudata so much that a worn individual might 
easily be mistaken for one of that species. The /. denudata is, however, distinguished 
by its single row of thick nodiform tubercles, the rounded dome-like shape of the pos- 
terior margin, and. the smooth upper surface of the body-whorls. Fig. 7 dis taken 
from the original specimen figured in ‘Mineral Conchology.’ This, and also the spe- 
cimens represented by figs. 7 a, e, form part of Mr. Wetherell’s collection. 
Size.—The largest specimen I have seen has lost the upper part of the spire, but 
when perfect, the dimensions would have been, axis, 2 inches, nearly; diameter 1 and 
1-10th of an inch. 
Localities.—Primrose Hill, Copenhagen Fields, Potter’s Bar. 
No. 98. VoLtuta puciu. F. 2. Edwards. Tab. XXII, figs. 1 a—e. 
VoLuta spinosa. Sow. 1850. Dixon’s Geol., &c., of Suss., p. 107; t. 5, fig. 16. 
= = var. PLATYSPINA. Sow. 1850. Dixon’s Geol., &c., of Suss., p. 107 ; t. 7, fig. 29 
V. testd ovato-oblongd, antice attenuatd, obscure costati, transversim sulcatd ; spird brevi. 
apice acuto: dnfractibus conveaiusculis, unicd serie spinarum coronatis ; spinis magnis, dis- 
