174 GASTEROPODA OF THE INFERIOR OOLITE. 



The body- whorl is similarly ornamented, and is slightly angular ; base full and 

 striated spirally with a very fine pattern, which slightly decussates with axial 

 lines. Aperture ovate-elongate ; columella straight and but little encrusted ; 

 anterior canal produced. 



Relations and Distribution. — Related to Cerithium abbas, var. C, this species is 

 still more like a Nerinsea. A single specimen from the Sauzei-bed at borne. 



Genus— Fibula, Piette, 1857. * Bull. Soc. Geol. France,' 2 me ser., vol. xiv, p. 556. 



The characters of this genus are not particularly well defined. Piette regarded 

 it as something between a Turritella and a Cerithium. Lycett (' Suppl.,' p. 16) 

 gives the following modified diagnosis : " 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 surface of the volutions is plain or 



slightly ornamented with oblique costse." Piette's types were Fibula undulosa 

 and F. nudiformis, to which Lycett added Fibula variata, Lye, F. eulimoides, 

 Whiteaves, and F. phasianoides, M. and L. All five are Great- Oolite species. 



M. Cossmann (' L'FJtage Bathonien,' p. 108, et seq.) more or less does away 

 with Fibula by merging it in Ceritella, so that, according to this arrangement, 

 F. undulosa, P., and F. nudiformis, P., become Ceritellse. 1 Fischer regards Fibula 

 as a subgenus of Ceritella. Whether Fibula is worth preserving as a genus or not 

 it is eminently a Bathonian group ; so also is Ceritella. Both are extremely rare in 

 the Inferior Oolite of England. The two species which I now propose to classify 

 under Fibula might possibly be allowed a place under Cerithium. The species in 

 the Inferior Oolite which I regard as belonging to Ceritella have the body- whorl 

 relatively longer and more approaching the cylindrical form. 



104. Fibula angustivoluta, sp. nov. Plate XI, fig. 1. 



Description : 



Length . . . . .12 mm. 



Width . . . . .4 mm. 



Ratio of body- whorl to entire shell . . 30 : 100. 



Spiral angle .... 25°. 



1 Fibula Eoyssii, d'Arch., comes under another category. 



