Emarginula. 
MOLLUSCA. 
103 
4. Pileopsis trilobus.— The Three-lobed Pileopsis, pi. 
XLVII. fig. 50 and 55. 
Pileopsis? trilobus. Phillips, II. p. 224, pi. 14, fig. 12, 13. 
Subconic, smooth, arcuated from the base to the vertex, 
which is straight, gradually tapering and acute at the vertex, 
pointing downwards, and nearly reaching the margin; aperture 
trilobate; base taking the undulous character of the lobes. 
Mountain Limestone of Bolland. 
5. Pileopsis tubifeu. —The Tubed Pileopsis, pi. XLVII. 
fig. 52. 
Pileopsis tubifer . Sowerby, VI. p. 224, pi. 607, fig. 4. 
Phillips, II. p. 224, pi. 14, fig. 14. 
Elongated, smooth, narrow, arcuated; vertex but slightly 
curved; three obscure, divergent, spinous ridges emanating 
near the vertex, and terminating on the margin, with three 
rows of long tubular spines, extending upwards of half an inch 
beyond the margin. 
Mountain Limestone, Bolland, and near Preston. 
6. Pileopsis vetustus -The Ancient Pileopsis, pi. 
XLVII. fig. 53. 
Pileopsis vetusta. Sowerby, VI. p. 223, pi. 607, fig. 1, 2, 3. 
Phillips, II. p. 224, pi. 14, fig. 19? 
Subconical, considerably arcuated, smooth; vertex blunt, and 
slightly bent; posteriorly contracted, and compressed on the 
sides; each with two or three irregular undulations, crossed by 
nearly obsolete, waved lines of growth; aperture oblong-ovate, 
broadest in front, the margin sinuous, conforming to the undu¬ 
lations. 
Mountain Limestone, Queen’s County, Ireland, Preston, and 
at Bolland. 
7. Pileopsis angustus. —The Straitened Pileopsis, pi. 
XLVII. fig. 54. 
Pileopsis angxistus. Phillips, II. p. 224, pi. 14, fig. 20. 
Subconic, spiral, smooth, narrow above; vertex turned to one 
side, obtuse; with transverse, wide-set lines of growth; aper¬ 
ture elongated, and expanded behind. 
Mountain Limestone, Bolland. 
Genus VI—FISSURELLA.— Bruguiere. 
Shell oblong, shield-shaped, or conically depressed; 
concave within; destitute of spiral convolutions; with 
the vertex perforated, and directed towards the front of 
the shell, the perforation subovate in some species, and 
nearly round in others; margin of the shell thickened 
around the inside, and generally crenulated; muscular 
impression visible near the inner edge, all round, widest 
on the sides near the front; outer surface striated, 
grooved, or radiated, from the vertex to the margin, and 
generally decussated by lines of growth. 
1. Fissurella Gr;eca.— The Greek Fissurella, pi. 
XLVIII. fig. 7, 8. 
Fissurella Greeca. Sowerby, V. p. 132, pi. 483. Fleming, 
p. 365. Patella Grceca^ Brocchi, II. p. 259* 
Oblong-ovate, convex, somewhat longitudinally arcuated, per¬ 
foration oval; whole surface with many small ribs, radiating 
from the apex to the base, composed of sets, consisting of one 
large and two small ones, and between each set is a still larger 
rib; these are intersected by numerous, transverse, elevated, 
narrow thread-like ribs, which produce a thickening at their 
intersections; inside oblong-oval, smooth; margin crenulated, 
and a little arcuated. 
The Crag at Ipswich. 
Genus VII—SIPLIO_ Brown. 
Shell ovate, subconic; vertex reflected, and slightly 
spiral; with a small dorsal fissure situate near the vertex, 
terminating internally by a rhombic, funnel-shaped sy¬ 
phon, or cup, in some species, but devoid of it in others; 
base ovate; exterior surface ribbed or striated. 
1. Sipho calthrata.— The Barred Sipho, pi. XLVIII. 
fig. 1, 2. 
Emarginula? s. Fissurella? clathrata. Sowerby, VI. p. 
33, pi. 519? fig. L Fissurella clathrata , Fleming, p. 365. 
Prominently conical; the vertex thick, and considerably in¬ 
curved, reaching nearly to the base; whole surface with strong, 
longitudinal, divergent ribs, emanating from the apex, and ter¬ 
minating on the base, each of which project beyond the edge, 
and form a crenulated margin, in the centre is a much thicker 
rib, with an awl-shaped fissure, extending from the back of 
the apex about half way down; these ribs are crossed by 
transverse ribs, which produce a beautifully reticulated aspect; 
aperture oval. 
The Oolite at Ancliffe. 
Genus VIII_EMARGINULA. — Lamarck. 
Shell conical, shield-shaped; vertex inclined to the 
posterior extremity; anterior margin with a notch, or 
fissure; internal cavity simple; anterior sides of the mus¬ 
cular impression interrupted, expanded, and not con¬ 
tinued across the front. 
1. Emarginula reticulata— The Reticulated Emar¬ 
ginula, pi. XLVIII. fig. 3, 4. 
Emarginula reticulata. Sow r erby, I. p. 74, pi. 33, lower 
figures. Fleming, p. 365. 
Greatly conical, elongated; vertex elevated, slightly turned 
to one side, but not acute; surface with twenty-four, or more, 
strong, divergent ribs, crossed by numerous thread-like stria?, 
which produce a fine reticulated appearance; fissure short; 
aperture oval; inside smooth. 
From the Crag, Holywells. 
2. Emarginula scarlaris. —The Ladder-like Emarginula, 
pi. XLVIII. fig. 5, 5,* 6. 
Emarginula scalar is. Sowerby, VI. p. 34, pi. 519, fig. 3. 
Fleming, p. 366. 
Conical; vertex but very slightly bent, somewhat eccentric, 
and obtuse; with many divergent, equal ribs, the central one 
cleft by the marginal fissure, the intervals crossed by very fine 
stria?; aperture obovate. Diameter a little more than an eighth 
of an inch. Fig. 5,* natural size. 
Found in the Oolite at Ancliffe. 
