Amastra forbesi
Species of gastropod
From Wikipedia, the free encyclopedia
Amastra forbesi is an extinct species of gastropod in the Amastridae family.[4]
| Amastra forbesi | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Order: | Stylommatophora |
| Family: | Amastridae |
| Genus: | Amastra |
| Species: | †A. forbesi |
| Binomial name | |
| †Amastra forbesi C. M. Cooke, 1917[3] | |
| Synonyms | |
|
Amastra (Metamastra) forbesi C. M. Cooke, 1917 · alternative representation | |
Description
The length of the shell attains 14.3 mm, its diameter 6.9 mm.
(Original description) The shell is imperforate, sinistral, elongate-conic, and thin, with a pure white coloration in its fossilized state. The spire's outlines are regularly and slightly convex, tapering to a rather sharp summit.
The whorls of the protoconch are slightly convex and indistinctly marked with minute striations. Subsequent whorls are also slightly convex, adorned with fine striations and delicate growth wrinkles. The body whorl is elongate, subcylindrical, and exhibits relatively coarse striations. It descends steeply near its base, forming a narrow, deeply curved area below the columellar fold.
The outer margin of the aperture is regularly curved and strengthened by a thick, prominent lip rib. The columella is short and broad, with a columellar fold that is moderately oblique and not particularly pronounced, tapering gradually just inside the columellar margin.[5]
Distribution
This species was endemic to Hawai, occurring in Pleistocene strata on Maui Island.
