186 EOCENE MOLLUSCA. 
columellar plaits, distinguish this species from the smooth variety of J/. parva, and 
from MV. gracilis. It is extremely rare: the specimen figured is, I believe, unique. 
Size.—Axis, 5-12ths of an inch; diameter, rather more than 2-1]2ths of an inch. 
Locality —Highceliff. 
No. 123. Mirra votutirormis. F. £. Edwards. Tab. XXIV, fig. 5 a—c. 
Mirra voLurirormis. Morr. 1854. Cat. Brit. Foss., 2d edit., p. 258. 
M. testd parva, oblonga, turritd, longitudinaliter costatd, antice transversim lineata, 
postice concentrice sulcatd, ceterum levi; spird exsertd, in longitudine dimidium totius 
teste superanti: anfractibus planis, antice subito coarctatis, ad suturas marginatis et 
unica serie tuberculorum instructis ; costis crebris, elevatis, rectis, fere ad basin tenden- 
tibus, postice nodulosis: aperturd angustd ; labro intus plicato ; columella quadriplicata ; 
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 Mitree, that it cannot be passed unnoticed. 
Size.—Axis, 3-12ths of an inch: diameter, somewhat less than 2-12ths of an inch. 
Locality.— Barton. 
