General characteristics
(Original description in German) The operculum perfectly resembles the shell of a Planorbis ; it consists of many slowly widening whorls that enclose an internal spiral cavity. On the body whorl a circular groove runs inward, which receives the simple peristome (lip) of the shell. Consequently, the edge of the operculum overlaps the margin of the shell aperture like the lid of a jar. The simple peristome does not lean against the previous whorl — a necessary feature to allow the operculum to overlap — which provides a means of distinguishing this genus from other cyclostomids even in the absence of the operculum.
The shell of the single species upon which I establish this interesting genus was collected in Ceylon by my unfortunate friend Dr. Hofmeister, who sadly passed away during his travels. In memory of its discoverer, I name it A. hofmeisteri. It is flat, almost disc-shaped, with a slightly projecting, very pointed spire, deeply impressed sutures, and a wide umbilicus. It is yellowish in color with brown bands and markings. Its diameter is 8 mm. [3]
(Description in German by Kobelt) The shell is low-turbinate to disc-shaped, with the body whorl detached at the front. The peristome (apertural margin) is free, straight, and continuous, fitting into a circular groove on the operculum. The operculum itself is not calcified and is slightly larger than the aperture; it is tightly coiled, planorbiform, and composed of two lamellae. Between these lamellae lies a spiral canal, while the outer edge features a groove designed to receive the peristome. [4]
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