Hemiplecta cymatium (Pfeiffer, 1856)
“Penang specimens, which slightly differ in the height of the spire agree in almost every point of structure with the type shell, described by Pfeiffer from Lancavi, a small island situated a few miles north of Penang. The increase of the volutions is in both exactly the same, the upper side of the whorls is marked with fine oblique rugosities, the lower is spirally striated; in fresh specimens the former is silky brown, the lower olivaceous brown, the inside of the aperture is in full grown specimens covered with a kind of a nacreous callose layer. The only noticeable difference consists in the narrowness of the umbilicus, its width being in all the Penang specimens, which I obtained, about one twelfth of the diameter of the shell, while in Benson’s type it is only one seventh of the same diameter.” (Stoliczka, 1873)
“The closely allied Rh. densa, only differs by a slightly smaller number of whorls, the last being much wider. Rh. chevalieri (Souleyet) differs in the same character, though it has the umbilicus of exactly the same size as the Penang variety of cymatium.” (Stoliczka, 1873)
“The animal is stout and rather short, its total length being less than twice the diameter of the shell; the posterior part of the body is the shorter one, and above rather sharply ridged; it ends with a large gland and a projecting horn above it. The whole body is uniform more or less dark brown, laterally strongly warty and obliquely grooved; the pedal row is very distinctly margined on both sides with an impressed line, and the margin of the foot below its is broad, smooth, marked with alternately brown and pale oblique stripe, so as to give the appearance of a variegated fringe. The eye peduncles and tentacles are of usual proportionate length, dark brown or even blackish, the latter with pale tips. On the whole, the general colour of the specimens varies a great deal; the young are mostly pale brown with an olivaceous tinge, while in old ones the neck, including the head and pedicles, become almost black.” (Stoliczka, 1873)
“The mantle is somewhat paler than the body, its edge moderately thickened. There are two small linguiform shell-lobes present, right one, just below the inner or posterior angle of the aperture of the shell, thus playing on the inner lip, and producing its moderately distinct nacreous and callose structure. The outer lobe lies below the outer periphery of the shell on the basal side; it projects from the outer end of a rather elongated very narrow fringe, which is separated from the edge of the mantle itself. The right neck-lobe is entire, thick, rounded, somewhat freely projecting at the lower or umbilical end. The left neck lobe is divided in two portions, the upper elongately rounded, the lower much narrower, with the upper end somewhat pointedly extended. The edge of the mantle which secretes the umbilical margin of the peristome is internally considerably thickened.” (Stoliczka, 1873)
“I have not been able to see satisfactorily the exact structure of the genital system, but, as far as it could be examined, it appears almost entirely to agree with that of Rhysota semiglobosa, figured by Semper. There certainly are no appendages present – neither on the penis, nor on the seminal duct or uterus.” (Stoliczka, 1873)
“The jaw is smooth, semilunar, with a rounded projection in the middle of the concave edge; it is about 2.5 mm broad. The radula is comparatively of very great length. In a middle-sized specimen it measured 7 mm in length and 3 mm in breadth, although one of the ends was not quite perfect. I counted 106 transverse rows and about 141 teeth in each row. The centre tooth has a comparatively short point without any lateral denticles, and is somewhat smaller than the adjoining laterals. The first of these has a long, laterally bent, rather blunt projection; the following very gradually decrease in size and the middle cusp becomes gradually more pointed and curved, while the basal plate decrease. With about the fifthieth tooth the end begins to become bicuspid, and on about the hundredth tooth on either side, the two cusps are sharpest and best developed.” (Stoliczka, 1873)
Other localities - “Perak” leg. R. Hungerford (Möllendorff, 1886); “Penang” (Stolizcka, 1873; Collinge, 1902)
“The species is found all over Penang hill from elevations of about 300 to 2500 feet, and both on the ground as well as on trees, but cheifly on the latter; it is, however, not common, and adult shells are indeed extreme rarities.” (Stoliczka, 1873)