Generic Character.—See Pl. 21.
- A. (div. 2.) testâ cinereo-albâ, fasciis duabus angustis fuscis, spirâ elongatâ rectâ, anfractibus 7 sub-ventricosis, labio interiore roseo, columellâ basi rectâ, integrâ, aperturâ ovato-oblongâ.
- A. Shell cinereous-white, with two narrow brown bands, spire elongated, straight; volutions seven, slightly ventricose, inner lip rosy, base of the columella straight, entire, aperture ovate-oblong.
- Obs. another specimen of A. pallida quite agreeing with this, is in Mr. Dubois' cabinet.
The species of this and one or two other genera of land-shells are subject to such variability in their colouring, that it becomes extremely difficult to ascertain which are species and which varieties. The shell now figured might, on a cursory glance, very well pass for one of the Protean varieties of the Linnæan Bulla fasciata; but a comparison with that shell will at once point out the strong specific difference that exists between them in the formation of the mouth. In this, the lower half of the inner lip, or more properly the pillar, is nearly straight; the base entire, or without any notch or truncated appearance: whereas in the true A. fasciata, the inner lip at the base is very much curved inward, and notched before it joins the outer lip. The mouth is also short and broad: whereas in this it is much more oblong, and the base round. Other more obvious characters exist in the form of the whorls, spire, and more particularly in the colour, of these two shells; but these are in comparison of minor importance.
I regret having but one example of this shell, as it prevents me from tracing how far the characters here detailed hold good in other specimens. They are such, however, as, I think, fully to justify the propriety of considering it a species.
Its locality is unknown.
I have little doubt more than one species exist among the supposed varieties of the true Bulla fasciata of Linn., which I take to be the shell figured by Lister.