348 GASTEROPODA OF THE INFERIOR OOLITE. 
281. Arapurus, cf. Lucipus, Thorent, 1839. Plate XXVIII, figs. 18a, 18d. 
1839. (Rorenia) Luctpa, Thorent, sp. Fide Cossmann, Etage Bath., p. 277, 
pl. vii, figs. 1, 2. 
Cf. also PLocostynus Typus, Gemmellaro. Faune Giuresi, p. 346, pl. xxviii, 
figs. 1 and 2. 
The specimen from the Oolite Marl of the Nailsworth district, figured in the 
accompanying plate, is unique as far as my collection goes. It has a basal 
diameter of 13 mm.; ratio of width to height as 10: 7. There is the possibility 
that this may be nothing more than a megalomorph of Ataphrus heliciformis, 
M. and L. D’Orbigny’s figure of Trochus lucidus (‘T. J.,’ ii, pl. ecexiv, figs. 5—7) 
differs from that given by Cossmann. 
282. ATAPHRUS HELICIFORMIS, Morris and Lycett, 1851. 
1851. ? Crossostoma HELICIFORME, Morris and Lycett. Great Ool. Moll. pt. 1, 
p. 73, pl. xi, fig. 8. 
1863. Monoponra nELicrrormis, Morris and Lycett. Lycett, Suppl., p. 123. 
Cf. also — ovutata, Héb. and Desl. Foss. Montreuil-Bellay, p. 58, 
pl. ii, fig. 9. 
Bibliography, §'c.—Although originally described as a fossil of the Great Oolite, 
the authors noted that C. heliciforme occurred in the middle division of the Inferior 
Oolite at Leckhampton. Monodonta ovulata seems to occupy an intermediate 
position between this form and the more abundant Ataphrus levigatus. 
Description.—In the majority of the specimens the basal diameter is about 10 mm. 
or rather less ; ratio of width to height as 4 : 3, being slightly less depressed than 
Ataphrus lucidus. 
The following is the original diagnosis :—“ Shell smooth, turbinated, some- 
what depressed: spire small, but little elevated; whorls rather convex ; aperture 
elliptical.” 
Relations and Distribution.—More depressed than Ataphrus levigatus, less so 
than the preceding species. Occurs at Stoford in Dorset, but principally in the 
Oolite Marl of the Cotteswolds, and in the Parkinsoni-zone of Aston and Not- 
grove. 
