G4 
MOLLUSCA. 
Pjleurotoma. 
Genus XXIV—CANCELL ARIA— Lamarck. 
Shell oval, subturreted; spire short in most species, 
but produced in a few; body large, ventricose, greatly 
exceeding the spire in length; aperture not quite entire, 
the base being for the most part somewhat extended into 
a canal, distinct in some cases, but always short and re¬ 
curved ; outer lip transversely sulcated within; inner lip 
reflected over the columella, and part of the front of the 
body; columella plaited, varying in number and size, for 
the most part they are large, compressed, and much de¬ 
pressed, in some instances they are small, few, and placed 
far within the columella, so as to be nearly obscured; at 
other times low down. 
1. C. QUADitATA.— The Square-shaped Canceilaria, pi. 
XXXVI. fig. 41, 42. 
Canceilaria quadrata . Sowerby, Min. Conch. IV. p. 83, pi. 
3G0. Fleming, Brit. An. p. 334. 
Oblong-ovate; spire of medium length, consisting of four 
inflated volutions, the body occupying about two-thirds the 
length of the shell, separated by a narrow suture, and termi¬ 
nating in a rather obtuse apex; whole shell provided with sharp, 
elevated, spiral, longitudinal, and very regular striae, the spiral 
ones the strongest; the intermediate spaces being small, 
hollow squares; aperture oblique, oblong-ovate, contracted both 
above and below ; inner lip broadly spread over the columella, 
on which there are two obtuse plaits, with a spiral fold on its 
edge ; outer lip sharp, entire, internally striated. 
Perfect specimens of this shell are to bo met with, varying in size 
from three-eighths of an inch to nearly an inch and a quarter. 
Found in the London Clay at Barton. 
2. C. evolsa.—T he Drawn-out Canceilaria, pi. XXXVI. 
fig. 4G, 47. 
Canceilaria evulsa. Sowerby, Min. Conch. IV. p. 84, pi. 
3G1, fig. 2, 3, 4. Fleming, Brit. An. p.334. Buccinum evul- 
sum, Brander, Foss. Plant, p. 13, pi. 1, fig. 14. 
Shell ovate, short; body large; spire short, consisting of five 
narrow, subturreted volutions, terminating in an acute apex; 
provided with varicose, longitudinal varices and ribs, crossed by 
many elevated, spiral striie, which are most prominent as they 
pass over the ribs and varices, with intermediate, less prominent 
striae, producing a roughness to the touch; aperture oblique, 
oblong-ovate, contracted both above and below; pillar lip 
broadly reflected on the columella, the base of which is pro¬ 
vided with two strong plaits and a spiral ridge, beneath which 
is a very short, rounded canal; outer lip sharp at the edge, 
with a strong varix behind, and striated internally. 
Found abundantly at Barton in the London Clay, as also at 
Lyndhurst, Southamptonshire. 
3. C. L/EViuscula.—T he Smoothish Canceilaria, pi. XXXVI. 
fig. 39, 40. 
Canceilaria Iccvmscula. Sowerby, Min. Conch. IV. p. 84, 
pi. 361, fig. 1. Fleming, Brit. An. p. 334. 
Shell short; body large; spire small, consisting of four in¬ 
flated volutions, well separated by the suture, and terminating 
in an acute apex; provided with longitudinal somewhat waved 
vai icose varices and ribs, crossed by numerous, obtuse, elevated 
striae; aperture oblique, rounded above, and contracted beneath; 
inner lip broadly reflected on the columella above, and nar¬ 
rowing as it descends, provided with two plaits, and a spiral 
ridge; outer lip a little thickened near the edge, and ribbed 
internally. 
Found in the London Clay at Higbgate, Barton, and Lynd¬ 
hurst. 
Genus XXV.—PLEUROTOMA.— Lamarck. 
Shell fusiform, turreted; spire generally longer than 
the body; aperture oval, with a canal more or less 
elongated at its base; outer lip with a notch or fissure 
at the upper part, contiguous to the suture; operculum 
horny, accumulated, its nucleus situate at the leaver 
extremity; some of the species are covered by a thin 
epidermis. 
1 . P. colon. — The Colon-marked Pleurotoma, pi. 
XXXVII. fig. 10. 
Pleurotoma colon. Sowerby, Min. Conch. II. p. 106, pi. 
146, fig. 7? 8. Fleming, Brit. An. p. 355. 
Fusiform; body and spire nearly of equal length; the latter 
consisting of six or seven subturreted volutions, terminating in 
an acute apex, these are concave above, witli their margins cre- 
nulatcd, and deeply divided by the suture; below the projecting 
margin, the body and volutions of the spire arc provided with 
numerous, rugged, spiral ridges, alternating, with fine stria*, 
which in some specimens divide the undulations into two small 
tubercles, crossed by many short longitudinal undulations, which 
arc frequently doubled in the same manner as the undulations; 
base conical; aperture oblong-ovate, nearly half the length of 
the shell, ending in an obtuse beak; diameter about a third of 
its length. 
Found in the London Clay at Barton Cliff. 
2 . P. semicolon. —The Semicolon-marked Pleurotoma, 
pi. XXXVII. fig. 5. 
Pleurotoma semicolon. Sowerby, Min. Conch. II.. p. 106, 
pi. 146, fig. 6. Fleming, Brit. An. p. 355. 
Elongated, turreted; body and spire nearly equal in length ; 
spire consisting of four or five inflated volutions, provided with 
granuated margins, which correspond with the long, narrow, 
curved spiral ribs; base of body conical, decussated; aperture 
ovote, one-third the length of the shell, ending in a nearly 
straight canal, which is a little expanding below; outer lip thin 
on the edge; pillar lip smooth, slightly reflected on the colu¬ 
mella. 
Found in the London Clay at Stubbington. 
3. P. comma. — The Comma-marked Pleurotoma, pi. 
XXXVII. fig. 8, 9. 
Pleurotoma comma. Sowerby, Min. Conch. II. p. 105, pi. 
246, fig. 5. Fleming, Brit. An. p, 355. 
Elongated, turreted; body somewhat shorter than the spire, 
consisting of five or six volutions, which, as well as the 
body are smooth in the middle, with numerous short, curved, 
elevated, longitudinal ribs on their superior portion, these are 
most prominent above, and pointed below in the form of com¬ 
mas; furnished with a few acute, elevated, sharp spiral stria?, 
