Cantharidus mortenseni: Shell globose solid, finely rimate, whorls flattened, angled above, obtusely rounded below, base slightly convex, suture impressed. Sculpture consisting of spiral ridges separated by a little narrower furrows, ridges beaded on the spire, smooth on the base, their number 5 on the penultimate whorl, 10 on the base: the 3 upper furrows on the penultimate whorl with a fine intercalating thread. Colour white with red spots on the ribs set in longitudinal series, spire crimson, grooves with a light greenish nacreous lustre. Protoconch smooth, white, of 1,5 whorls, the following 5 whorls spirally lirate. Aperture quadrangular, oblique, iridescent and lirate within, outer lip thin, slightly indented. Columella vertical, white, with a submedian tubercle and a narrow callous reflection; no callous covering on the parietal wall. Dimensions: H. 5.5 mm, d. 5.2 mm.
DESCRIBED BY Odhner as Gibbula mortenseni.

Cantharidus mortenseni: New Zealand. Type location: Auckland Island, Carnley Harbour, 45 fms, sandy clay.