124 American Se ash 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 



Plate 31 



Southeast Florida. 



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 



Plate 3h 



Southeast Florida and the West Indies 



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 



Plate 3) 



Southeast Florida and the West Indies. 



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 



