16 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
Genus—Fipuua, Piette, 1857. 
Description des Cerithium enfonis dans les dépéts bathoniens de |’Aine et des Ardennes, par M. Ed. 
Piette, ‘ Bull. de la Soc. Géol. de France,’ 20 Avril, 1857. 
M. Piette has founded his proposed genus upon a small group of lengthened spiral 
univalves which possess characters intermediate and approximating them to Turritella and 
to Cerithium. A rounded, straight columella, with a rudimentary umbilical groove near 
the base, is combined with an arcuated outer lip slightly notched posteriorly at the suture ; 
the base of the aperture forms a slight canal at its junction with the anterior extremity of 
the columella, or in other instances there is no canal, the base being rounded and entire, 
depending upon the exact period of growth at which the animal perished; the surface of 
the volutions is plain, or slightly ornamented with oblique coste. The author has figured 
and described several species, and has characterised his genus in the following terms :—* Le 
principal charactére du ce genre est d’avoir une columella droite. Le bord libre est arqué, 
légérement échancré a sa partie posterieure, pres de la suture. L’ombilic n’est souvent 
que rudimentaire, a peine indiqué, et affectant seulement la columelle externe. D/autres- 
fois, il pénctre tout le spire. Un caractére trés curieux que j’ai remarqué sur plusieurs 
especes de ce genre, mais que je n’ai pu encore constater sur toutes, c’est que la columelle 
se termine parfois interieurement par un canal rudimentaire; que le mollusque forme ce 
canal et le rebouche tour a tour, pour le former ensuite de nouveau en grandissant. 
Ainsi il arrive souvent que parmi plusieurs /i4u/a dune méme espece, les 
unes semblent se rapprocher des Cerithium, les autres des Turritelles. Cela dépend du 
moment ou elles ont péri.” 
In admitting the generic value of Fibula, it becomes necessary to arrange with it the 
following Jurassic Testacea :—Chemnitzia phasianoides (Mor. and Lyc.), Cerithium Rotssit 
(Mor. and Lyc.), Zurritella Roissii (D’Arch.), and Cerithium suturale (Buvignier). The 
Great Oolite of Oxfordshire and of Minchinhampton has supplied the two following 
additional species. : 
Fisuna variata, Lyc. Tab. XXXL, figs. 4, 4a. 
Testa turriculata, subventricosa ; spira elongata, acuta, leve, anfractibus (11—12) con- 
veaviusculis, angustis, suturis valde impressis ; ultimo anfractu symmetrico-curvato ; columella 
interdum ad basin subcanaliculato, aut integro, labro sinistro arcuato. 
Shell turriculated, somewhat inflated; spire lengthened, acute, smooth, consisting of 
11 or 12 narrow, somewhat convex volutions, with deeply impressed sutures; the last 
yolution is conformable with the others, and. is symmetrically curved towards its anterior 
