PLEUROTOMARIA 433 
374, PLEUROTOMARIA OXYTERA, sp. nov. Plate XXXVII, fig. 6. 
Description : 
Height : : : : . 35 mm. 
Basal diameter 5 : : . 55 mm. 
Spiral angle . : : : SEK 
Shell conical, trochiform, moderately umbilicated. Spire regular or very 
slightly concave ; apex sharp. Number of whorls about eight; those at the apex 
slope regularly, but presently become subgradate, sutures close and not cana- 
liculate. The spiral system of ornament is strong, undulating, and rather wide 
apart; there is a diadem of regular and rather fine tubercles at the angle and 
another at the base of each whorl, which is subbicarinate. 
The sinus-band is median, prominent, and pretty wide, but varies in the 
different whorls; showing from one to three spirals, though this feature is effaced 
in the body-whorl, where it is somewhat flattened. The posterior area of the 
body-whor! is mostly without tuberculation, but the lower keel is very prominent 
and nodular, showing a strongly dentate periphery. Base convex, without marked 
spiral ornament, deeply but not widely umbilicate, and very actinomphaloid, the 
larger specimens being smoother. Aperture subrhomboidal and oblique. 
Relations and Distribution.—Distinguished both from Pl. Actea and Pl. 
actinomphala by its conical habit and sharp spire, it approaches the latter in the 
character of its ornamentation, whilst the actinomphaloid base is a feature shared 
by all three species. It is very directly connected with the acute variety of 
Pl. actinomphala, but the umbilicus is always smaller, and there are other 
differences. 
I have three specimens from the Sauzei-bed, Oborne. 
375. PLevROTOMARIA ACTINOMPHALA, Deslongchamps, 1848. Acute variety, Plate 
XXXVII, figs. 7a, 7b, and Plate XX XVIII, 
fig. 5. Obtuse variety, Plate XXXVIII, 
figs. 1—4. 
1848. PLevROTOMARIA acTINOMPHALA, Deslongchamps. Vol. cit., p. 32, pl. xviti, 
fig. 1. 
1854. = — — D’Orbigny, Terr. Jur., 
vol. li, p. 458, pl. ecclxxiv. 
1873. — — — Tawney, Dundry Gas- 
teropoda, p. 49 (41). 
