CHAPTER XXII: THE HELMET SHELLS. 

 CAMEO SHELLS 



Family Cassidid.^ 



Shell heavy, thick, sub-globular, or three-cornered; spire 

 short; whorls sometimes varicose; aperture long, ending in front 

 in a recurved channel; columella thick, widely spread out, with 

 folds; outer lip thickened at margin and toothed within; oper- 

 culum horny, concentric, fan-shaped; head large; tentacles with 

 eyes at base; snout extensible; foot large; mantle large. 



An energetic, predatory family, living along sandy shores 

 of warm oceans, and preying upon various bivalve mollusks. 



Genus CASSIS, Lam. 



Characters of the family. Twenty-five species. 



The Red Helmet or Bull's Mouth (C. rufa, Linn.) has a 

 cowry-shaped brown shell, oval in outline, but with a broad spire. 

 The surface is finely cancellated. The body whorl has three rows 

 of low knobs. The broad, toothed lips are clouded and barred 

 with bright orangeTred, shading darker between the teeth. A 

 wide enamel callus coats the columella. Length, 5 to 7 inches. 



Habitat. — Indian Ocean, Japan. 



The Black or Cameo Helmet Shell (C. cameo, Stimps.) 

 was wrongly njamed C. Madagascarensis, by Lamarck, for it is 

 not an inhabifknt of Oriental seas. It is yellowish with brown 

 markings. Tae distinguishing character is the painting with dark 

 brown of the spaces between the ridges that surround the aperture. 

 These cross streaks are short and distant on the lip; longer and 

 close-set on the columella. Three spiral ridges revolve about 

 the body whorl, bearing knobs. Length, 10 inches. 



Habitat. — Beaufort, N. C, to West Indies. 



The Sardonyx Helmet (C. tuberosa, Linn.) has a three- 

 cornered outline, and the surface is crossed by fine lines, both 



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