186 EOCENE MOLLUSCA. 



columellar plaits, distinguish this species from the smooth variety of M. parva, and 

 from M. gracilis. It is extremely rare : the specimen figured is, I believe, unique. 



Size. — Axis, 5-12ths of an inch j diameter, rather more than 2-12ths of an inch. 



Locality. — Highcliff. 



No. 123. Mitra volutiformis. F. E. Edwards. Tab. XXIV, fig. 5 a — c. 

 Mitra volutiformis. Morr. 1854. Cat. Brit. Foss., 2d edit., p. 258. 



M. testa parva, oblongd, turritd, longitudinaliter costatd, antice transversim Uneatd, 

 postice concentrice sulcata, cceterum lavi : spird exsertd, in longitudine dimidium totius 

 testa superanti : anfractibus planis, antice subito coarctalis, ad suturas marginatis et 

 unicd serie tuberculorum instructis ; costis crebris, elevatis, rectis, fere ad basin tenden- 

 tibus, postice nodidosis : aperturd angustd ; labro intus plicato ; columella quadriplicatd ; 

 labio angustissimo, postice incrassato. 



Shell small, oblong, turreted, longitudinally ribbed ; spire elevated, exceeding the 

 aperture in length ; whorls five or six, exclusive of the embryonal whorls, with the 

 sides nearly straight, and contracting suddenly towards the base, where they present 

 five or six transverse, coarse, raised lines ; the sutural margin is bordered by a single 

 row of round tubercles, corresponding with the ribs ; the posterior surface is con- 

 centrically furrowed ; the middle surface smooth ; the ribs, which are numerous, 

 prominent, and straight, extend to the transverse raised lines on the base, and 

 terminate, posteriorly, in a double row of knobs or tubercles, somewhat larger than 

 those which run round the suture, and from which they are separated by a deep 

 furrow. The aperture is lanceolate, and, owing to the contraction of the whorls, 

 terminates anteriorly in a short, narrow canal, which is slightly emarginate in front ; 

 the outer lip is plicated within ; the inner lip very narrow, and thickened near the 

 suture, where it forms an oblong callus ; the columella is slightly curved, and furnished 

 with four oblique folds, gradually increasing in size as they ascend the columella. 



The specimen figured is, I believe, unique. It is apparently an immature shell ; 

 but the characters are so strongly marked, and so distinct from those of the other 

 English Eocene Mitrae, that it cannot be passed unnoticed. 



Size. — Axis, 3-12ths of an inch : diameter, somewhat less than 2-12ths of an inch. 

 ality. — Barton. 



