Leptochiton columnarius (Hedley & May, 1908)

(Figure 46H)

The examination of photographs of the holotype of L. columnarius indicated that the antemucronal slope of the tail valve is one and a half times longer than the postmucronal slope. This is probably why this species was later placed in the genus Parachiton by Iredale & Hull (1925). L. columnarius is very similar to L. subantarcticus by its highly or very highly arched valves, but differs from the latter by having a posterior mucro.