CHAPTER LVI : THE KEY-HOLE LIMPETS 



Family Fissurellid^b 



Shell broadly conical, elevated or flattened, not pearly, 

 with apical or anterior anal slit, or hole; operculum wanting; 

 gills, a pair, symmetrical; head well developed, with short muzzle, 

 eyes on outer bases of tentacles on rudimentary stalks; siphon 

 occupying notch or hole; foot fleshy, with fringed border. 



This large family contains more than a dozen genera and 

 over one hundred species. The slit or key-hole distinguishes the 

 adult shells from those of the limpets proper. In habits the 

 mollusks are much like Acmaea and Patella. 



The young key-hole limpet begins life with a spiral shell 

 and a njarginal slit. Gradually shelly matter is added which 

 unites the margin below the slit, and the spiral seems to uncoil. 

 It finally disappears, the slit having travelled upward and replaced 

 it at the apex of the shell. 



Genus FISSURELLA, Brug. 



Shell steeply conical, limpet-like, but with hole in apex, 

 bounded internally by a thickened band or callus; lining white, 

 porcellanous ; body when at rest contained in the shell. 



The Volcano Key-hole Limpet (F. volcano, Rve.) is sig- 

 nificantly named. Its steep cone looks like the ash crater of the 

 typical volcano of our geographies. A touch of realism is added 

 by the red stripes that radiate from the apical hole, like streams 

 of molten lava pouring down the sides. 



Shells of this species are common on beaches of Southern and 

 Lower California. Very strangely, dead and worn shells are much 

 brighter than living ones. They are ashen pink with purple rays 

 when alive ; the mantle is striped with red and the foot is yellow. 

 They creep about on the rocks, and may be seen at low tide. 



F. Barbadensis, Gmel., I found on the Keys outside of 

 Charlotte Harbour on the west coast of Florida. Its steep cone is 



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