102 
1. Ancylus elegans. —The Elegant Ancylus, pi. XLVII. 
fig. 32 and 35. 
Ancylus elegans. Sowerby, VI. p. 64, pi. 533. Fleming, 
p. 280. Brown, Elts. Foss. Conch, p. 64, pi. 4, fig. 14. 
Subconical, rather convex, smooth; apex pointing obliquely 
to one side, and situate near the narrower end of the shell; 
aperture subovate, narrower at the apicial end, and more point¬ 
ed, the opposite extremity rather flattened; surface covered 
with extremely minute, divergent strife, which are only disco¬ 
verable by the aid of a strong lens. Height nearly equal to 
half its greatest diameter. 
Dark-gray sand of the London Clay at Hordwell. 
Genus IV.—CALYPTRiEA.— Lamarck. 
Shell conical; vertex subcentral, imperforate, and 
acute; base of aperture orbicular, or nearly so, its mar¬ 
gins sharp and entire; internal cavity provided with a 
lateral salient appendage, or septum, which varies much 
in form in different species; various species have a 
strongly marked, muscular impression, just above the 
fold of the inner lip; in other species, it is situate on the 
outside of the inner cup, but never within it. 
SECTION I-TROCHIFORM, THE SEPTUM SOMEWHAT SPIRAL. 
1. Calyptr;ea eciiinulatum. —The Spined Calyptraea, 
pi. XLVII. fig. 36, 37. 
Infundibulum echinulatum. Sowerby, I. p. 221, pi. 97, fig. 
2. Fleming, p. 363. 
Smootn, conical, depressed, oblique, inflated on the sides; 
with three or four spiral convolutions, the apicial one acute, and 
two or three lower ones smooth; body with regular series of 
rather obscure, short spines, which are most developed near the 
edge. Diameter three-quarters of an inch. 
Plastic Clay at Plumstead. 
2. Calyptraea rectum. —The Rectangular Calyptraea, pi. 
XLVII. fig. 38, 39. 
Infundibulum rectum. Sowerby, I. p. 220, pi. 97, fig. 3. 
Fleming, p. 362. 
Conical; apex central; body inflated; spire with two or three 
obsolete volutions, ending in an acute, nearly central vertex; 
aperture nearly circular; internal plate rectangular, and with 
one volution; columella slender; external surface concentrically 
striated. 
The Crag at Ilolywells. 
3. Calyptraea obliquum —The Oblique Calyptraea, pi. 
XLVII. fig. 40,41,42. 
Infundibulum obliquum. Sowerby, I. p. 220, pi. 97, fig. 1. 
Fleming, p. 363. 
Subconic, somewhat depressed, very smooth, oblique; vertex 
turned to one side; aperture circular; internal transverse parti¬ 
tion reaching two-thirds across the inside, its edge reflected near 
the columellar region, and having the aspect of an umbilicus. 
Fig. 42, natural size of the shell. 
London Clay, Barton Cliff, and at Brakenhurst, Surrey. 
PlLEOPSIS. 
4. Calyptraea spinulosum— The Spinous Calyptreca, pi. 
XLVII. fig. 46, 47. 
Infundibulum spinulosum. Sowerby, I. p. 222, pi. 97, fig. 
6. Fleming, p. 363. 
Subconic, ventricose; with three or four obscurely defined 
volutions, the superior ones slightly inflated; vertex nearly 
central, the apex acute; surface covered with numerous, small, 
extremely short, somewhat reflected hollow spines; aperture 
orbicular; outer lip curved internally; the transverse septum 
reaching three-fourths across the cavity; slightly twisted at the 
base of the columella, producing the appearance of a subum¬ 
bilicus. Diameter nearly an inch and a half. 
London Clay at Barton Cliff. 
5. Calyptraea tuberculatum —The Tuberculated Ca¬ 
lyptraea, pi. XLVII. fig. 45. 
Infundibulum tuberculatum. Sowerby, I. p. 221, pi. 97, fig. 
4, 5. Fleming, p. 363. Trochus apertus, Brander, Foss. 
Hant. pi. 1, fig. 1, 2. 
Subconic, inflated, oblique; spire with two or three volu¬ 
tions, apex obtuse; whole surface covered with spiral bands of 
rugose tubercles; aperture subrotnnd. 
London Clay, Hampshire. 
Genus V.— PlLEOPSIS. — Lamarck. 
Shell obliquely conical, posteriorly recurved, with an 
uncinate spiral apex; the volutions serrated, and rolled 
inwards; aperture large, ovate; anterior margin shortest, 
the posterior one large, and rounded; inside with two 
elongated, arcuated, muscular impressions, situated under 
the posterior margin; external surface covered with a 
thick, horny, somewhat pilous epidermis. 
1. PlLEOPSIS UNGUIS—-The Hoof Pileopsis, pi. XLVII. 
fig. 43, 44. 
Patella xinguis. Sowerby, II. p. 88,* pi. 139, fig. 7. Capu- 
lus unguis , Fleming, p. 364. 
Subdepressed, suborbicuiar; vertex recurved, oblique, extend¬ 
ing beyond the margin, the convolution small and acute; base 
suboval, contracting internally; outer lip even. Height about 
a third of its width. 
Found in the Crag at Holywells. 
2. Pileopsis striatus -The Striated Pileopsis, pi. 
XLVII. fig. 49. 
Pileopsis striatus. Phillips, II. p. 224, pi. 14, fig. 15. 
Oval; apex placed near one end; vertex incurved, and free; 
arcuated from the base to the vertex; outer surface covered 
with strong, sharp, radiating striae, crossed by numerous, remote, 
transverse lines of growth ; base suboval. 
Mountain Limestone, Northumberland, Bolland, and County 
of Kildare, Ireland. 
3. Pileopsis Neritoides. —The Nerita-formed Pileopsis, 
pi. XLVII. fig. 48 and 51. 
Pileopsis Neritoides . Phillips, II. p. 224, pi. 14, fig. 16, 
17, 18. 
Obliquely spiral; spire depressed, with two volutions, the 
apex blunted; aperture oval; outer surface with strong, irregu¬ 
lar lines of growth, and concentrically striate at the base. 
Mountain Limestone at Bolland. 
MOLLUSCA. 
