after passing the gill, the excretory pore, and the 

 anus. The queen conch Cassis cameo and the king 

 conch Stronihiis gii^cis of warmer coasts in the Atlan- 

 tic, Caribbean, and Gulf of Mexico produce shells 10 

 to 12 inches long, covering animals weighing up to 

 five pounds. These shells are much sought for ship- 

 ment to Europe (particularly Italy) as the material 

 from which cameos are carved. The trumpet shell 

 Charonia tiiionis is similar but more slender; it 

 reaches a length of 20 inches in the Gulf of Mexico 

 and also in the Indian Ocean. 



Cowries (Cypraea and other genera — Plate 58) 

 produce massive shells too, with such strikingly hand- 

 some patterns that they are favorites with collectors. 

 Yet the shell of a live cowry rarely shows unless the 

 animal is disturbed, for the shell-secreting mantle 

 covers its product almost completely. Many cowries 

 have the habit of dissolving out the inner whorls 

 of the shell, making more room for their bodies and 

 salvaging the lime as material to be added in en- 

 larging the outer whorl. In the South Pacific certain 

 small cowries have served as money, and been car- 

 ried like perforated coins strung on cords. 



In former times even greater value was attached 



to the murex snail Miirex tmnciiliis of the Mediter- 

 ranean, one of a large genus with perhaps a thousand 

 species around the world. M. trunculiis produces in 

 its anal glands a brownish fluid which, upon exposure 

 to air, oxidizes to a substance which man has used 

 for thousands of years as a dye — Tyrian or royal pur- 

 ple. The ancient Tyrians did not know how to re- 

 move the glands. They obtained the secretion 

 through the crude technique of crushing the whole 

 body of the snail in bowl-shaped cavities along the 

 rocky coast. They filtered the fluid and treated it in 

 various secret ways to purify it, making the material a 

 mysterious substance. It has proved to be one of the 

 most beautiful, colorful, and permanent dyes for 

 cloth. Yet the snail itself is almost equally striking, a 

 predator that creeps rapidly and can swim too, in 

 spite of a medium-weight shell with elongated siphon 

 canal and a large number of ornamental ribs and 

 spines. 



A close relative of Murex is Vrosalpinx. the oyster 

 drill, which causes thousands of dollars' damage an- 

 nually by cutting through the shells of oysters and 

 clams and removing the commercially valuable meat, 

 killing one victim after another. 



Under surface of a limpet, Acmaea, at left shows the head and large muscular foot, mantle 

 edge, and a feathery gill at left of head. Only sensory tentacles on the head protrude beyond 

 the upper surface of the shell, at right. (Maine. Ralph Buchsbauni) 



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