download pdf

124 American Seash ells
spina Lamarck. The latter, however, is a distinct species from the West
Indies which is characterized by a splotch of bright orange-red around the
umbihcal region (see pi. 3I).
Astraea americana Gmelin American Star-shell
Southeast Florida.
Plate 31
1 to I /4 inches in length, % as wide. Characterized by its sharp-angled
spire, flat sides, white to cream color, and by the numerous, long, wavy,
weak, axial ribs. Base of shell with 5 to 8 small, finely fimbriated, spiral
cords, and a small ridge at the base of the columella which has about a dozen
small axial ridges. Commonly found under rocks at low tide on the Lower
Florida Keys. Operculum variable, but usually thick, convex and with a
small or large dimple.
The subspecies, imbricata Gmelin, from the West Indies has stronger,
longer and fewer axial ribs which extend to the flat base of the shell and are
hollow at their ends. The subspecies guadeloupensis Crosse from the Greater
Antilles is intermediate between these two. Both moderately common at
low water.
Subgenus Lithopoma Gray 1850
Astraea caelata Gmelin Carved Star-shell
Southeast Florida and the West Indies
Plate 3h
2 to 3 inches in length and width. Similar to A. tuber, but with 9 to 10
spiral rows of numerous, hollow, scale-like spines on the lower % of the
last whorl, 5 of which are on the base of the shell. Operculum thick, convex,
and finely pustulose. Moderately common in the West Indies.
Astraea tuber Linne Green Star-shell
Southeast Florida and the West Indies.
Plate 3)
I to 2 inches in length, equally wide. Characterized by the peculiar
green-and-white, cross-hatched color scheme, by the low, blunt, smooth axial
ridges, and by the smoothish base of the shell. Sometimes mottled in soft
browns. Common below low water in the West Indies, rare in Florida.
Operculum with a thick, arched, tapering ridge on the exterior (like a large
comma).
Subgenus Pomaulax Gray 1850
Astraea undosa Wood Wavy Turban
Plate i8p