The Slipper Shells. Cup-and- saucer Limpets 



tell the story plainly. The horseshoe crab (Limulus) often carries 

 a load of upward of one hundred slippers. Length, i to 2 

 inches. 



Habitat. — Maine to Brazil. 



The Flat Slipper Shell (C. plana, Say, C. unguiformis. 

 Lam.) is found flattened against the walls of apertures of dead 

 shells. Growth proceeds, and the broadening shell of the slipper 

 becomes concave on the back, parallel to the concavity of the 

 body whorl within which it is attached. Examine the shells of 

 Natica for slippers of this peculiar form. 



The shell is usually white, the apex claw-like, as Lamarck's 

 scientific name defines it. The pointed end is fitted with a tri- 

 angular shelf. The other end is broad like a spade. According 

 to Professor Conklin, the female is fifteen times as large as the 

 male. This species is small and frail. Length, i inch. 



Habitat. — Maine to Florida. 



C. aculeata, Gmel., is common on Florida and California 

 beaches. Smaller than the arched slipper, it resembles it in 

 being marked with brown, and having a white "seat" in the 

 end. The shell has radiating ribs which bear faint knobs. 



This species has a remarkable world-wide distribution on 

 warm beaches. 



C. glauca is a little hump-backed species that keeps company 

 with the small hermit crabs which live in the dead shells of the 

 dog whelk. It is an Atlantic coast form. 



The Pacific coast has several slipper shells. C. aculeata and 

 C. plana are there. C. adunca, Sby., with high apex strongly 

 recurved, is about an inch long. It is brown with a white shelf 

 inside. This is the most common western species. 



The W^rinkled Slipper Shell (C. dorsata, Brod.) is nearly 

 round in outline, and often bent so that the shelf is two-lobed 

 resembling the twisted cup in some species of Calyptraea. The 

 thin, flat shell is brown and white, and about f inch long. It is 

 common on California beaches. 



The White Slipper (C. Lessonii, Brod.) is handsomest in 

 the form that wears ruffles on its shell, along the lines of growth. 

 It is distinguished by its whiteness, its flatness and by the delicacy 

 of its shelf. There is much variability in this Californian species. 



C. dilatata, Lam., is i ^ to 2^ inches long, a broad oval shell, 

 heavy, with shaggy surface and undulating margin, brown 



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