PROSOBRANCHIATA. 161 



Section A. (Pullus small, conical. "\ 



a. Shell turbinate or pyriform ; costated or coronated; > continued, 

 inner lip effuse ; columellar plaits few) J 



/3. Transversely furrowed at the base only. 



No. 99. Voluta athleta. Solander. Tab. XXI, figs. 7 a — e. 



Steombus athleta. Soland. 1766. Brand. Foss. Hanton., p. 31 ; t. 5, fig. 66. 



Voluta — Sow. 1823. Min. Con., vol. iv, p. 133 ; t. 396, figs. 1—3. 



— — Defr. 1829. Diet, des Sci. nat., vol. lviii, p. 480. 



— — Desk. 1824-37. Desc. des coq. foss., vol. ii, p. 689; t. 93, figs. 12 



—13. 



V. testa rhomboidali, spinis magnis dispansis coronatd, ad basin sub-profunde emar- 

 ginatd ; spird brevi, acuminata: anfractibus postice Icevibus, ad basin obsolete transversim 

 sulcatis : aperturd effusd ; labro tenui, simplici ; labio parum effuso, postice incrassato ; 

 columella depressd, leviter arcuatd, tri-plicata. 



Var. Fortis (tab. 2\,fy. 7 e) testa ovato-turbinatd, breviori, latiori ; anfractibus 

 antice valde attenuatis. 



Shell rhomboidal, crowned with large spreading spines, and widely, but not deeply, 

 notched at the base ; spire rather short and pointed. In young individuals, the 

 whorls are transversely furrowed, obscurely ribbed, and surmounted by two rows of 

 short, erect spines ; but as the shell approaches maturity, the ribs become effaced, the 

 second, or sutural row of spines disappears, and is replaced by an irregular sharp 

 elevated line, and the spines of the first row become large, distant, and spreading ; the 

 transverse furrows disappear after the first three or four whorls, and the shell is after- 

 wards smooth, except at the base, where a few faint, almost obsolete, transverse furrows 

 appear. The aperture is elongate, and rather wide ; the outer lip smooth and simple ; 

 the inner lip moderately spread over the body whorl, thickened at the upper part, 

 and not extending backwards beyond the suture ; columella flattened in front, slightly 

 curved, and presenting one broad prominent fold in front, and two or three others, 

 small and indistinct, behind. 



A variety occurs at High cliff, which appears to correspond with the shell described 

 by M. Deshayes, more closely than do the Barton shells ; it is more turbinate, 

 shorter, and comparatively wider than the type, and the whorls are much attenuated 

 in front. 



The smooth and ventricose body and flattened columella distinguish this species ; 

 and at maturity, the large spreading spines give a strongly marked character to it. 



Size. — Axis, 3 inches, nearly; diameter, 1 inch and 7-10ths, nearly. 



Localities. — Barton, Alum Bay (No. 29, Prestwich). For the variety, Highcliff. 

 French : Monneville, Houdan (fide Desh.). 



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