The Turban Shells and Star Shells 



The colour is dirty white, texture calcareous, aperture pearly- 

 Hned; the operculum is smooth, white, rounded, with a depres- 

 sion in one side. Height, i inch; diameter, 2 inches. 



Var. spinulosum, Lam., is found on the Florida coasts. 

 It has a higher cone than the typical longispina, has no umbilicus, 

 and its spines, tubercles and the basal laminae are much reduced 

 in size. The average specimen is i^ inches in altitude, and 2 

 inches across the base, but the ratio of height to diameter is 

 variable. The specimens examined are decorated with brownish 

 streaks and speckles. 



A. latispina, Phil., is a high cone, armed with triangular 

 spines of small size along the outer margins of the whorls, and 

 short, oblique ridges between. The dull white surface is streaked 

 with brown and yellow. The base has spiral ridges crossed by 

 fine striae. This species is ij inches high and 2 inches in diameter. 



Habitat. — Gulf of Mexico to Rio de Janeiro. 



Sub-genus LITHOPOMA 



A section of Astralium containing very solid, turban-shaped 

 shells, with the whorls radiately folded or plaited, and the peri- 

 phery rounded or keeled. 



The Stone Apple {A. tuber, Linn.) is a heavy turban-shaped 

 shell, distinguished by the regular diagonal plaiting of ridges 

 and valleys that alternately follow down its whorls. The colour 

 follows the plan of sculpture; the valleys are dark, the elevations 

 light. Brown and pale green overlie the dirty white ground 

 colour. The base is paler and has finer markings. A little 

 rubbing exposes the pearly interior substance. 



A character that keeps this species in the genus Astralium 

 is the presence of spinous processes around the periphery of young 

 shells; these ultimately wear off. Elsewhere, in the genus Turbo, 

 such processes become more prominent as growth proceeds. 



This West Indian shell occurs on East Florida beaches. It 

 attains an altitude of two inches and an equal diameter. 



A. Americanum, Gmel., is of the same stony group, but with 

 a still higher cone. The diameter of i to ij inches is generally 

 a trifle less than the altitude. The whorls are keeled on the 

 outer edges; oblique folds cross them, and end in a row of nodules 

 on the keels. 



Habitat. — Florida Keys and throughout the West Indies. 



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