Shell rimate, rather solid, oblong, turreted, reddish towards the
apex, elsewhere dark purple-red or almost black, variegated with
oblique, more or less zigzag, opaque creamed-coloured stripes, some of
which extend from suture to suture, others only a short distance from
the top of the whorls. The latter are 7½ in number, scarcely convex
or almost flat, and very feebly constricted beneath the suture. The
upper ones are finely granosely decussated, the last and the penultimate being smooth and merely marked with the oblique incremental strise. All exhibit a fine plication or puckering beneath the
suture, beneath which an impressed line is sometimes observable
upon the last and preceding volutions. Aperture bluish within,
displaying more or less of the external striping, vertical, equalling
about two fifths of the shell's length. Columella suberect, bluish
and dark violet, scarcely forming any angulation at the base with the
lower margin of the peritreme. Length 36 millims., diam. 17;
aperture 14½ long, 8 wide.
This handsome shell approximates very closely to A. heuglini of
Martens in form, but has certain differences in colour and sculpture,
which, however, may prove to be only varietal. A. heuglini, from
South Abyssinia and the Gazelle River, is said to be regularly striated,
and of a horny lutescent colour flamed with red. A. martensiana,
on the contrary, is finely granosely decussated upon the spire, and the
coloration is very rich and striking. The dark purplish red, which
ill some specimens is almost black, predominates; and the opaque,
obliquely somewhat zigzag stripes upon the back of the body-whorl
in several shells are abruptly terminated in an oblique line which
marks a period of growth. Between the larger creamy stripes which
reach from suture to suture in the upper whorls, and extend over
the whole extent of the last, there are minor streaks and spots flowing only a short distance beneath the suture.
