Height 52 mm, breadth 25 mm. Shell thick and solid, ovoid except for elongated siphonal canal. Varix presents at every 120°. Two to five axial ribs between adjoning varices, overridden by some 10 slender, sharp and brown spiral ribs making intersections granulous. Spines risen on the varix, most prominent on the shoulder, below which present 2-3 medium sized spines with smaller spinelets in between. (Even in “spineless" specimens, the shoulder spine recongnizable). Aperture oval with crenulated outer lip. Siphonal canal slender, straight, as long as the shell height with at least 1-3 spines on the right. Operculum horny with anteriorly situated nucleus.
Distribution:
Guayana and off Suriname.
Remarks:
As was demonstrated by Bayer (1974) there is a wide variability in prominency of spines. Abbott (1974) took this species as a form of M. cabritii, but they are easily separable from each other.