The Slipper Shells. Cup-and-saucer Limpets 



This strange limpet-like creature is found near Iceland and 

 off Martha's Vineyard, at 69 to 458 fathoms depth. In the South 

 it appears off the Florida Keys and the West Indies. The average 

 specimen is i^ to 2 inches across, at base, and i to i^ inches high. 



Twenty fossil species are known, the earliest from Silurian 

 rocks. 



THE HORSE-HOOF SHELLS 



Genus AMALTHEA, Schum. (HIPPONYX, Defr.) 



Shell thick, obliquely conical; apex hooked backward, not 

 spiral; surface roughened; muscle scar horseshoe shaped; body 

 oval; foot thin; head round, on slender neck; tentacles bearing 

 eyes. Instead of an operculum, a shelly base is formed. 



The Horse-hoof Shell (A. antiquata, Linn.) is found in 

 Florida and California and in many other sub-tropical regions. 

 It is a concave, hoof -shaped white shell with a hairy epidermis 

 covering the scaly growth lines. The shape is variable, for the 

 animal lives attached to rocks. It secretes a calcareous plate 

 between the body and the object to which it adheres. Sowerby 

 thought this was a second valve of the shell, and so described 

 five species as a genus of bivalve mollusks. 



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