DIAGNOSIS: A Columbarium with a gradate spire of moderately convex whorls bisected by the keel. Posterior whorl slope smooth; anterior whorl slope of spire smooth and on the body whorl bearing the anterior carina and a spinose lira immediately posterior to it
DESCRIPTION: Shell fusiform with a moderately elongate spire of shouldered whorls cut by a median keel bearing laterally directed keel spikes. Posterior whorl slope convex and smooth. Anterior whorl slope flat and smooth on the spire, and on the body whorl flat, then rapidly contracted to the keel and bearing a prominently spinose lira immediately posterior to the anterior carina. Aperture subquadrate. Canal long and only slightly twisted bearing four or so spinose lirae or with numerous fine lirae bearing prominent scales.

The population of C. spinicinctum from off Cape Morton exhibits dimorphism. Both forms are exactly alike in size, shape, colour pattern and pattern of sculpture, but differ in degree of development of keel spikes and spines on the lirae of the body whorl and canal. One form, described and illustrated by Martens, has longer and fewer spikes on the keel, and the lirae of the body whorl and canal have well developed spines; the other form, described as C. caragarang by Garrard, has more numerous blunt keel spikes, less prominent spines on the lirae of the body whorl and scales on the canal. Garrard (1966, p. 10) suggests that 'the differences could possibly be due to sexual dimorphism* and this may well be, but as yet the animal of either form has not been studied. In view of the variability of some of the populations of fossil species e.g. that of C. acanthostephes and the fact that the pattern of sculpture is identical, there are no grounds for maintaining C. caragarang as a separate species.

LOCATION OF TYPES: Institut fur Spezielle Zoologie und Zoologisches Museum der Humboldt-Universitat zu Berlin: Holotype 26677; Australian Museum, Sydney: Holotype of C. caragarang C64800; National Museum of Victoria: Hypotype F26251, J. Berrie Collection.
OCCURRENCE: Off Cape Morton in vicinity of type locality, Queensland. 70-100 fathoms.