POTAMIS. 
MOLLUSCA. 
67 
In some specimens the tubercles on the superior portion of the 
volutions have a coronated appearance. 
Found in the Blue Clay, or Plastic Clay, above the indurated 
Marie, Castle-hill, near Newhaven, Sussex, and at I lord well 
Clin’. 
5. C. py ram i dalis. — The Pyramidal Cerithium, pi. 
XXXVII. lig. 28, 29. 
Cerithium pyramidalis. Sowerby, Min. Couch. II. p. 61, 
pi. 127, fig. 1> 1. Cerithium liexagonum , Lamarck, Env. de 
Paris, p. 79. Murex hexagonus , Chemnitz Conch. X. p. 261, 
pi. 162, fig. 1554-5. Murex angolosus , Brander, p. 24, fig. 46. 
Fleming, Brit. An. p. 397- 
Pyramidal, turreted ; body occupying about a third of the 
shell; spire consisting of nine or ten volutions, provided with 
six prominent, tuberculated ribs, all the volutions having three 
transverse, tuberculated, slightly arcuated, obtuse carinre, each 
with three tubercles, corresponding to the number of carina* 
which cross them; the upper portion of the body volution 
furnished with six compressed tubercles, and seven or eight 
carina?, and is destitute of cost® on its lower portion ; whole 
surface covered with minute, transverse or spiral stria?; aper¬ 
ture somewhat orbicular, terminating in a short, twisted canal; 
outer lip expanded, undulous, but smooth on the edge; pillar 
lip broadly reflected on the columella. 
Found in the London Clay at Barton Cliff and Hordwell 
Cliff. 
Genus XXVII.—NEIIINEA— Defrance. 
Shell turreted, oblong, subcanaliculated, with numer¬ 
ous volutions; aperture subquadrate; columella provided 
with a strong fold, also one on the outer lip, and one on 
the inner lip at the edge of the body. 
1. N. Goodiiallii _Goodhall’s Nerinea, pi. XXXVII.* 
fig. 2, 3. 
Nerinea GoodhalliL J. dc C. Sowerby, in Geological Trans. 
2nd Ser. IV. p. 348, pi. 23, fig. 11. G. B. Sowerby, Junr., 
Conch. Man. fig. 374. 
Turreted, smooth ; provided with numerous concave volu¬ 
tions, half as long as they arc wide; interior with three plaits, 
one situate on the columella, one opposite it, and another above 
it within the volution; aperture rhomboidal. 
Fig. 3 represents a section of the shell, which exhibits its gene¬ 
ric character. 
Found by Dr. Fitton in the Oxford Oolite. 
Genus XXVIII.—POTAMIS.— Brongniarte. 
Shell turreted; aperture almost semicircular, but des¬ 
titute of a canal in the upper angle; base contracted 
into a short, slightly truncated beak; outer lip dilated, 
provided with a horny operculum, in the recent con¬ 
dition. 
1. P. politus. — The Polished Potamis, pi. XXXVII. 
fig. 21. 
Cerithium politus. Sowerby, Min. Conch. IV. p. 50, pi. 
339, fig* 3. Cerithium melanoides , Ibid. II. p. 109? ph 147, 
fig. 6, 7. Fleming, Brit. An. p. 358. 
Subulate, smooth, shining, turreted, with obscure longitudinal 
undulations; body not quite one-third the length of the shell; 
spire consisting of ten or eleven volutions, which are very 
convex in the centre, and separated by a very distinct suture; 
above the centre of the volutions is a spiral carina, which is 
beset with large, oblong tubercles, with two or three spiral 
tuberculated carina below, and usually with four on the body 
volution; aperture nearly circular, terminating in a very short, 
slightly curved canal. 
Found in the Plastic Clay at Southfleet, Hamsay, near Croy¬ 
don, Kent, and plentifully at Charlton. 
2. P. dubius —The Doubtful Potamis, pi. XXXVII. fig. 
20 . 
Cerithium duhium. Sowerby, Min. Conch. II. p. 108, pi. 
147, fig. 5. Fleming, Brit. An. p. 358. 
Subulate, turreted; body about a third of its whole length ; 
spire consisting of ten volutions, with a spiral carina of sharp, 
compressed, ovate tubercles near the centre, and two series of 
lesser tubercles below; base with one or two belts of tubercles; 
aperture nearly circular, terminating in a very short, twisted 
canal. 
In this species the tubercles are situate about one-third the length 
of the volutions from its upper edge ; and differs from the P. poli¬ 
tus in the tubercles being sharper. 
Found in the London Clay at Stubbington. 
3. P. funiculatus —The Rope-like Potamis, pi. XXXVII. 
fig. 35. 
Cerithium funiculatum . Sowerby, Min. Conch. II. p. 107, 
pi. 147, fig* 1, 2. Fleming, Brit. An. p. 358. 
Pyramidal, tapering abruptly; body about one-third the 
length of the shell; spire with ten or eleven volutions, flattened 
on the sides, and separated by a shallow suture, provided with 
four nearly equal, crenulated, rope-like carina?, the upper and 
largest one situate near the margin of the volutions, the next 
one the smallest, the whole being nearly equidistant from each 
other; aperture almost circular, ending a very short, slightly 
twisted canal; margin of the outer lip plain. 
The carina? in this shell strongly resemble closely knotted ropes. 
Found in the Plastic Clay at Plumstead. 
4. P. intermedius. — The Intermediate Potamis, pj. 
XXXVII. fig. 32. 
Cerithium intermedium. Sowerby, Min. Conch. II. p. 107, 
pi. 147, fig. 3, 4. Fleming, Brit. An. p. 358. 
Pyramidal; body about a third of the length of the shell, 
consisting of twelve or thirteen gradually diminishing, flat-sided 
volutions, their superior margins closely bounded by a thick, 
deeply crenulated carina, with four or five unequal, plain, or 
subtuberculated and irregular carina, crossed by strong and 
sharp lines of growth ; several elevated ridges on the base of 
the body ; aperture subovate, rounded above, and terminating 
below in a short, slightly bent canal. 
Found plentifully in the Plastic Clay at Charlton. 
This species may be distinguished from the P. funiculatus by the 
irregularity of its kecds. 
5. F. rigidus. —The Rigid Potamis, pi. XXXVII. fig. 
30, 31. 
Potamides rigidus. Sowerby, Min. Conch. I \ . p. 48, pi 
