PROSOBRANCHIATA. 159 



No. 97. Voluta tricorona. Sowerbg . Tab. XX, figs. 7 a — d. 



Voluta tricorona. Sow. 1843. Min. Con., vol. vii, p. 6; t. 613, fig. 2. 



V. testa ovato-rhomboidali, costatd, transversim sulcata, antice profunde emarginatd ; 

 spird brevi, a/pice acuta ; anfractibus obtuseangulatis, triplici serie spinarum nodiformium coro- 

 natis ; costis numerosis, angustis, fere ad basin tendentibus ; sulcis transversis irregularibus, 

 lineis incrementi decussatis .- aperturd elongato-ovdli, postice subcanaliculatd ; labro simplici, 

 Icevi j labio effuso ; columella biplicatd. 



Shell rliomboidal-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, deep, 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 V. 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 ^is 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 

 l-10tli of an inch. 



Localities. — Primrose Hill, Copenhagen Fields, Potter's Bar. 



No. 98. Voluta pugil. F. E. Edwards. Tab. XXII, figs. 1 a—c. 



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. testa ovato-oblongd, antice attenuatd, obscure costatd, transversim sulcata ; spird brevi, 

 apice acuto ; anfractibus convexiusculis, unicd serie spinarum coronatis ; spinis magnis, dis- 



