34 MOLLUSCA FROM THE GREAT OOLITE. 



cum aliis minoribus alternates, suturis carinatis, carinis clatis et Icevigatis, basi planulatd, 

 canali brevissimo; aperturd subquadratd. 



Shell turreted, conical, excavated; whorls (10) concave, narrow, with numerous trans- 

 verse very fine lines, alternating with others still more faintly impressed ; the sutures are 

 carinated, the carinse elevated and smooth, the base flattened, the canal short. Aperture 

 subquadrate. 



The general aspect of our species approaches near to the Cerithium Defrancii of 

 M. Deslongchamps, whose figure however is less conical, and the concavity of the whorls 

 is much less. These differences, however, are only such as may pertain to varieties of the 

 same species. It is rare ; and the few examples which have occurred to us are composed 

 entirely of crystalline carbonate of lime, which does not allow of the internal characters 

 being fully determined ; as far as we can observe them, the outer lip is simple, and the 

 columella plicated with one fold, and the upper portion of the volution has a very slight 

 fold. This shell belongs to the subgenus Trochalia, Sharpe; but to the species having the 

 columella solid and not hollow. 



Locality. The upper portion of the shelly beds near to Minchinhampton and 

 Chalford. 



NERIN^A DUFRENOYI, Arch. sp. Plate VII, fig. 8, Sa 8e. 



CERTTHIUM DCFRENOYI, Archiac. 1843. Mem. Soc. Geol. Fr., vol. v, pi. 31, figs. 3, 4. 

 D'Orb. 1850. Prod. Paleont., p. 303. 



N. Testa parvd, cylindrico-subulatd ; anfractibuslatis,planatis, costutts cinctis, etnodu- 

 lafis; cingulis 4 out 5, indsfUxKbnt dense-nodulatis, cingula infra suturam valdc elatd, et 

 Iceviyatd, sine nodulis. Anfractibus lineis perpendicwlaribus, interstitialibus dense et 

 tenuissime instructis. Aperturd elongatd, columella solidd, plicis duabus ? parvis; plied 

 caiernd unicd, magnd. 



Shell small, cylindrical, or subulate ; the whorls wide, flattened, encircled with costse, 

 which are nodulated ; the encircling bands are 4 or 5, unequal and closely, but sometimes 

 imperfectly, nodulated ; the band nearest to the upper suture the largest and most elevated, 

 it is nearly smooth, and without nodules. The surface of the volutions has also very 

 closely-arranged fine perpendicular lines visible iipon the interstices of the cinctures. The 

 aperture is elongated and narrow ; the columella solid, with two small folds ; the outer lip 

 has a single, much larger fold. 



The perpendicular length of the whorls is nearly equal to their transverse diameter ; the 

 sutures are strongly marked. The usual length of this species does not exceed an inch, 

 the number of volutions in large specimens not exceeding ten. The coarseness of the 

 Great Oolite rock is not favorable to the preservation of the more delicate features of this 

 pretty and fragile species, so that in the greater number of instances the surface of the 



