PLEUROTOMARIA. 427 
368. PLEUROTOMARIA ARMATA, Miinster, 1844. Plate XXXVII, fig. 5. 
1844. Prevrotomarta arMATA, Miinster. Goldf., Petref., pl. 186, fig. 7. 
1848. — -~ — Deslongchamps, vol. cit., p. 39, pl. ii, 
fig. 2; pl. in, fig. 2. 
1854. — — — D’Orbigny, Terr. Jur., vol. 1i, p. 451, 
; pls. ecelxviii, ecclxix. 
1873. _ — — Tawney, Dundry Gasteropoda, p. 50 
(42). 
Syn. _ DENTATA, Deslongchamps. Vol. cit., p. 37, pl. iv, figs. 1 
and 2. 
Bibliography, §c.—Mimster’s species was originally described from the ** Upper 
Oolite”’ of Streitberg and Vigors; but since it has been identified by Deslong- 
champs, d’Orbigny, and other paleontologists as a fossil of the French Bajocian, 
there is no need to step behind their conclusion. 
Description (especially applicable to the var. Miinsteriana, Deslongch.) : 
Height : : ; : . 60 mm. 
Basal diameter ; d 2 conmim: 
Spiral angle (approx. i : = 100% 
Shell thick, trochiform, subdbnrssed, deeply umbilicated. Spire convex. 
The whorls, six in number, are angular and step-like in their increase, the angle of 
the whorl being situate about one third the way down, the upper third being nearly 
flat, and the remaining two thirds nearly vertical. The keels carry thick nodula- 
tions at rather wide intervals, and at the base of the lower whorls is a set of 
tuberous undulations. The sides of the shell are ornamented by richly-cut spirals, 
which are large and flexuous towards the anterior margin. Sutures rather close 
and undulating. 
The sinus-band is placed about the middle of the height of the whorls ; it is 
wide, flat, and spirally striated, but in the body-whorl smooth and strap-like. 
The body-whorl is bicarinate, the upper carina being grossly nodular as in the rest 
of the shell; whilst the lower carina, situate on the basal periphery, is bluntly 
angular and ornamented with a series of striated undulations rather than nodules, 
these become fainter anteriorly. Base convex, with marginal striz and sometimes 
a marginal furrow; nearly smooth towards the centre, but spirally striated in the 
cavity. The umbilicus is somewhat funnel-shaped, and very deep. Aperture 
nearly circular, with some obliqueness of the outer lip. 
The var. precatoria, Deslongchamps, has a less depressed spire and some slight 
differences of ornamentation. 
Relations and Distribution.—This species is one of the most vigorous and charac- 
