ATAPHRUS. 351 



Bibliography, fyc. — Our Inferior Oolite specimens appear somewhat more 

 elongated than the Bathonian types, yet not so dissimilar but what they may be 

 referred to d'Archiac's species. " Nerita " bellulata, Bean, which I include here, 

 is perhaps more close to Monodonta papilla, H. and D. (' Foss. Mont.-Bellay,' p. 59, 

 pi. iii, fig. 1). In fact, At. Labadyei, At. papilla, and At. Acmon have at least this 

 feature in common, viz. that they are smooth trochiform shells, where the height 

 and width are about equal. 



Description : 



Height of full-sized specimens . . .15 mm. 



Width, about ..... 15 — 16 mm. 



Shell conoidal, subturbinate, smooth, tolerably thick. Spire elevated, the apex 

 very obtuse. Whorls about six, subconvex and prominent, standing out well from 

 the suture. The body-whorl is large, slightly depressed posteriorly, rounded at 

 the angle, and subconvex in the base. Aperture restricted and almost circular, 

 with a moderate columellar denticle, succeeded anteriorly by a very shallow sulcus 

 or pit. 



Relations and Distribution. — Distinguished from At. Acmon by the prominence 

 of the whorls. At. Labadyei, and the varieties therewith included, are also more 

 widely distributed throughout the Inferior Oolite. 



Although in the main a Great Oolite species, At. Labadyei occurs in the Lower 

 Division of the Inferior Oolite both in Dorset and in the Cotteswolds. It also 

 occurs in the Clypeus-grit and in other localities and horizons ; whilst in the 

 Dogger it is represented by the var. bellulata, Bean. N.B. — Should there be any 

 disposition to challenge the identification of At. Labadyei as an Inferior Oolite 

 species, I would suggest that the forms from the Lower Division be classified as 

 Ataphrus bellulatus. 



286. Ataphrus Acmon, d'Orbigny, 1850. Plate XXIX, figs. 11 and var. fig. 12 ; 



var. approaching Ataphrus papilla, 

 H. and D., fig. 13. 



1850. Tbochus Acmon, d'Orbigny. Prod., i, p. 265. 



1852. — — — Terr. Jur., vol. ii, p. 278, pi. cccxiv, figs. 1 — 4. 



1873. Monodonta Acmon, d'Orb. Tawney, Dundry Gasteropoda, p. 35 (27). 



1884. Atapheus Acmon, d'Orb. Cossmann, Etage Bath., p. 281, pi. vii, figs. 9, 10. 

 Cf . also — Hebeeti, Piette. Cossmann, op. cit., p. 281, pi. xvii, figs. 43, 44. 



Bibliography, fyc. — This is essentially a Bajocian form, the types being from 

 Bayeux and Port-en-Bessin ; also abundant at Sully ; all places where the fossili- 



