66 



MOLLUSCA. 



Cerithicm. 



strongly striated to the base of the body; outer lip wing-shaped, 

 and nearly semicircular; aperture elongated, and oblique; inner 

 lip narrowly reflected on the columella. 



Found in the London Clay at Hordwell. 



11. P. L^viGATA The Smooth Pleurotoma, pi. XXXVII. 



fig. 8, 9. 



Pleurotoma Icsvigata. Sowerby, Min. Conch. IV. p. 120, 

 pi. 387, fig. 3. Fleming, Brit. An. p. 355. 



Elongated, turreted, almost smooth ; body and spire nearly 

 of equal length ; spire consisting of seven ventricose volutions, 

 a little concave above, well defined by the suture, and provided 

 with rather flattened, longitudinal ribs; a few obscure spiral 

 strise invest the shell, and some nearly obsolete lines of growth ; 

 aperture oblong-ovate, pointed above, and ending below in a 

 short, almost straight, narrow canal, which with the aperture is 

 nearly equal to the spire in length. 



Found in the London Clay at Muddiford and Highgate Hill, 

 London. 



Genus XXVI.— CERITHIUM.— ^n^^rMf^re. 



Shell greatly lengthened, turreted; with numerous 

 volutions ; more or less tubercular, or spinous, or rough, 

 in a very few instances smooth, or spirally grooved; 

 aperture subquadrate or ovate, its upper part modified 

 within by the abdominal region of the body ; the outer 

 lip or peritreme a little thickened, and sometimes broadly 

 reflected, with a groove at its upper extremity ; columella 

 arcuated, with a sharp spiral plait at its base, and form- 

 ing the upper margin of the canal, which is somewhat 

 short, truncated, and generally reflected; aperture closed 

 by a small horny operculum. 



1. C. CORNUCOPIA The Horn of Plenty Cerithium, pi. 



XXXVn. fig. 17. 



Cerithium cornucopi(e. Sowerby, Min. Conch. II. p. 197, 

 pi. 188, fig. 1, 3, and 4. Terebra cornucopia; Fleming, Brit. 

 An. p. 347. 



Subulate, turreted, punctated ; with upwards of thirty vari- 

 ously ornamented volutions, terminating in a rather acute apex; 

 volutions contiguous to the apex, with one crenulated keel, 

 situated a little under the centre; in those immediately suc- 

 ceeding, the margin imperceptibly assumes a tuberculated 

 appearance, and a small knobbed carina rises between it and 

 the middle one, with its lower edge crenulated ; the tubercles 

 on the upper margin gradually increase, the central keel 

 becomes more depressed, while other carina? arise on each side 

 of it in the central volutions, tuberculated above, undulated 

 below with four or five transverse furrows; these carinas 

 become broader, and the intermediate spaces assume the form 

 of furrows, while the crenulations and tubercles continue in 

 an undulating series, those on the upper edge being elongated, 

 and towards the interior portion of the shell unite with the 

 undulations under them, and gradually supercede the furrows ; 

 from this point they by degrees recede from the margins, 

 and on the two or three lower volutions, as well as the body, 

 assume the form of oblong, obtuse, somewhat oblique knobs, 

 nine or ten in number ; whole surface covered by minute 



punctures disposed in lines, which diverge as they pass over the 

 tubercles, and converge as they descend ; aperture quadrate, 

 terminating in a short, narrow, curved canal, its edge rising on 

 the columella in the form of a plait ; outer lip semicircular ; 

 columella with three strong, oblique plaits, and frequently pro- 

 vided with a ridge above, on the base of the body. 



This shell is subject to great variety of aspect in its progress 

 from the young to the adult condition, and varies in length and 

 breadth in the full grown shell. It frequently exceeds a foot in 

 length, the diameter of the body being one-fourth the length of the 

 shell. 



Founil in the London Clay, mixed with Green Sand, under 

 Stubbington Cliff. 



2. C. GiGANTEUM. — The Gigantic Cerithium, pi. XXXVII. 

 fig. 18. 



Cerithium giganleum. Lamarck, Env. de Paris, p. 95. 

 Knorr, III. pi. 107, fig. !• Parkinson, Organic Rem. III. p. 

 71. Sowerby, Min. Conch. IL p. 199, pi. 188, fig. 2. Terebra 

 gigantea, Fleming, Brit. An. p. 347. 



Subulate ; body short ; spire very long, gradually tapering, 

 consisting of numerous, fluted, minutely punctured volutions, 

 which are separated by a shallow and narrow suture ; superior 

 portion of the volutions slightly nodulous, below which are 

 six or seven equidistant, nearly obsolete transverse striae ; aper- 

 ture ovate, contracted above and below, columella having four 

 plaits. 



This shell is said to attain the extraordinary length of thirty 

 inches, while the diameter of the body volution is seven and a half 

 inches. 



3. C. GEMINATUM. — The Gemmed Cerithium, pi. XXXVII. 

 fig. 22, 23. 



Cerithium gemminatum. Sowerby, Min. Conch. II. p. 63» 

 pi. 127, fig. 2, 2. Fleming, Brit. An. p. 357. 



Elongated, turreted, conical, smooth ; body and spire of 

 nearly equal length ; the latter consisting of ten or eleven 

 turreted volutions, terminating in an acute apex ; each volution 

 provided with seven or eight pairs of longitudinally disposed 

 tubercles, the upper pair the largest, particularly on the body 

 volution, where it is frequently bifid; the body is also furnished 

 with two rows of very small tubercles ; two nearly obsolete, 

 transverse carina; uniting one pair of tubercles to the succeed- 

 ing ones ; aperture nearly orbicular, terminating in a slightly 

 recurved canal; outer lip even; inner lip pretty broadly reflect- 

 ed on the columella. 



Found in the London Clay at Barton Cliff. 



4. C. FUNATUM. — The Corded Cerithium, pi. XXXVII. 

 fig. 15, 16. 



Cerithium funatum. Sowerby, Min. Conch. II. p. 64, pi. 

 128. Fleming, Brit. An. p. 358. 



Conical, elongated, tapering gradually to a somewhat pointed 

 apex ; body about half the length of the spire, which consists 

 of nine or ten volutions, each of which is furnished with two 

 obtuse crenulated spiral ridges, thickened and tuberculate on 

 their superior portion, which strongly resemble the twisting of 

 a cord ; body volution differing from the others, in being gar- 

 nished with two additional transverse ridges ; aperture some- 

 what quadrangular, terminating in a slightly twisted, short 

 canal ; base smooth ; outer lip even on the edge ; pillar hp 

 reflected on the columella, narrowed at its connexion with the 

 body, and widening towards the centre. 



