408 GASTEROPODA OF THE INFERIOR OOLITE. 
The following is the original diagnosis :—‘‘ Shell conical, regular ; whorls 
straight-sided, ornamented with rows of separate tubercles, placed obliquely in 
opposite directions on either side of the sinus-band. Above the band are three 
rows of compressed tubercles ; below it are three of smaller round tubercles, and 
then three to four larger ones which form the angle in the last whorl [vide Pl. 
XXXV, fig. 1]. Sinus-band [submedian] with a central salient ridge, and crossed 
by curved lines ; base of last whorl slightly convex. The umbilicus was probably 
closed.” 
Relations and Distribution.—Tawney was at some pains to point out how the 
ornaments of this species differ from those of Pl. punctata. However, the almost 
median position of the sinus-band would seem altogether to remove it from the 
section to which Pl. punctata belongs. The pecuhar Dundry matrix gives 
emphasis to the ornamentation on which the author largely based his specific 
characters. 
It is met with sparingly at Dundry, and shells which most nearly approximate 
to this form occur in the Sauzei-bed, or subzone, at Oborne and Milborne Wick. 
These have no umbilicus, and the aperture is almost quadrate with a straight 
inner lip. 
344. PLEUROTOMARIA SOROBINULA, Deslongchamps, 1848. Plate XXXYV, figs. 3 and 
3a, and ? fig. 2. 
1848. P.LEevRoTOMARIA SCROBINULA, Deslongchamps. Vol. cit., p. 60, pl. ix, fig. 4. 
1854. _— — _: D’Orbigny, Terr. Jur., vol. 11, 
p- 501, pl. ecexciv, figs. 4—6. 
Description : 
Height : : : : 5 AN remnant, 
Basal diameter 5 ‘ a! » 20)mm: 
Spiral angle . ; , (HOP GR. 
Shell small, conical, scarcely craniliostad! Suite regular or very slightly 
convex. Whorls (about seven) flat or scarcely angulated, suture close; the 
ornaments consist of a tolerably uniform system of fine spirals which are more or 
less reticulate, the reticulation being best seen in the earlier whorls. 
The sinus-band is almost median, of fair width and prominence, with 
ornaments which vary from a single spiral with cross-lines (see Pl. XXXV, 
fig. 3a) to almost smooth. The body-whorl is relatively large and bluntly 
angular at the periphery ; base rather flat with faint spiral striz, and sometimes 
a very slight umbilical pit occurs. Aperture rhomboidal to square, the inner lip 
being straight and reflexed at the extremity so as to form a widish gutter. 
