PLEUROTOMARIA. 409 
Relations and Distribution—The specimens referred to Pl. scrobinula occur for 
the most part in the Parkinsoni-zone, where they are by no meansabundant. The 
one figuredis from Woolston. The agreement with Deslongchamps’ description is 
substantial, though he describes Pl. scrobinula as having a smooth base—a 
feature possibly due to wear. 
Fig. 2 represents a specimen from the Cadomensis-bed, Clatcombe (top of the 
Humphriesianus-zone), where the spire is rather more convex and the whorls 
slightly undercut, and the sinus-band is broad and with little apparent ornament ; 
there is no umbilicus whatever. This may be a variety of Pl. scrobinula, but the 
ornamentation is rather coarser. In fact, this shell seems to occupy a position 
between Pl. Dundriensis and Pl. scrobinula. 
345. PLevroromarta ALoyong, d’Orbigny, 1850. Plate XXXV, figs. 4, 4a, 40. 
1850. Prevroromaria ALcyons, d’Orbigny. Prod., i, p. 268. 
1854. _ _ — Asay diniesy oll a, jos chet yall 
ecelxxxix, figs. 6—10. 
Description : 
Height : ; ; : . 20 mm. 
Basal diameter : : : . 23 mm. 
Spiral angle . 5 : ; Oy. 
Shell conical, trochiform, moderately umbilicate. Spire regular. Whorls 
(seven) subconvex, with a slight belt developed at the base of each. Spiral 
ornaments fine throughout, but strongly reticulate from oblique radu in the 
posterior area of the whorls. 
The sinus-band is submedian, rather narrow, and slightly sunk; carries one 
central spiral crossed by growth-lines, is sometimes smooth. The body-whorl is 
angular at the periphery, subconvex, and has the ornamentation subdued, the 
base being almost smooth; umbilicus small and rather steep, with curved radii 
springing from the margin. Aperture subrhomboidal and depressed. 
Relations and Distribution.—The figured specimen, from the Parkinsoni-zone of 
Burton Bradstock, answers well to the description and figures of Pl. Aleyone in 
the ‘ Terrains Jurassiques.’ It is rare. 
346. Prevroromaria AtHuLta, d’Orbigny, 1850. Plate XXXIV, fig. 12. 
1850. PLevRroroMaria Aruuttia, d Orbigny. Prod., i, p. 269. 
1854. — — — Terr. Jur., vol. ui, p. 489, pl. 
ecelxxxix, figs. 11—16. 
