78 EOCENE MOLLUSC A. 



No. 27. Pupa oryza. F. E. Edwards. Tab. XIV, fig. 3 a — b. 



P. testa parvd, ovato-cglindraced, ad utramque extremitatem equaliter attenuatd ; apice 

 sub-obtuso; a/nfractibus octonis, convexiusculis, lorigitiidinaliter tenuissime costellatis ; suturis 

 profundis ; aperturd ovato-oblongd, angustd, obliqud, quaternis dentibus magnis instructd. 



A small cylindrical oval shell, tapering equally towards both extremities ; the apex 

 is rather blunt ; the whorls, which are eight in number, are slightly convex, separated 

 by a deep conspicuous suture, and transversely costellated; the costellse are numerous, 

 very slender, and oblique. The aperture is ovate-oblong, narrow, and somewhat 

 oblique ; the outer lip is furnished with four prominent lamelliform teeth, of which 

 the two anterior are the longest. 



I possess only one specimen, a cast, of this species ; and the state of the aperture 

 does not enable me to say whether the columellar lip is furnished with teeth. The 

 species appears to be perfectly distinct. 



Size. — Axis 2 lines; diameter 1 line. 



Locality. — Headon Hill. 



Genus 10th. Clausilia.* Draparnaud. 1805. 



Gen. Char. — Shell sinistral, cylindrical, elongated, consisting of numerous volutions, 

 generally transversely striated ; rather blunt at the apex, and enlarged towards the 

 middle ; aperture irregular, oval ; peristome continuous, free, reflected, with several 

 columellar and other tooth-like plaits, and furnished with an appendage, termed the 

 clausium, attached to the columella, by which the aperture is partially closed when the 

 animal is withdrawn into the shell. 



The clausium, from which the present genus derives its name, answers the purpose 

 of an operculum, with which, however, it presents no further analogy than that it 

 serves to enclose and protect the animal within the shell. It consists of a narrow, flat, 

 and very thin calcareous pedicle attached by the posterior extremity to the columella, 

 and expanding at the opposite end into a linguiform plate, which nearly closes the 

 aperture of the penultimate whorl, a small canal across the anterior part of the aperture 

 being left uncovered, probably for the purpose of respiration. In some species when 

 the outer lip presents teeth, the clausium is notched for their reception. This curious 

 appendage is formed when the animal approaches maturity, probably at the same time 

 with the projected reflected mouth. The pedicle is very flexible, and yields to the 



* Etym. Clausium, (quasi clausus, closed, or claustrum, a door,) the appendage by means of which the 

 animal is enclosed in the shell. 



