CHAPTER XXXV: THE PYRAMID SHELLS. 

 OBELISK SHELLS 



Family Pyramidellid^ 



Shell slenderly spiral, of many whorls, coiled to the left; 

 aperture entire; columella with one or more folds; operculum 

 horny; foot extending far beyond head; proboscis long, retractile; 

 radula wanting; tentacles flattened, ear-shaped, channeled 

 outside. 



This family includes but one genus in which living species 

 exist. They are believed to be carnivorous, despite the deficient 

 mouth parts. 



Genus PYRAMIDELLA, Lam. 



Characters of the family. Tropical seas. 



The Obelisk Shell (P. conica, C. B. Ads.) is our represen- 

 tative of this genus. It occurs in Florida and at San Diego, 

 Cal. Its ten flat whorls are separated by a deep spiral suture. 

 It has a slender brownish spire half an inch high. Three folds 

 are seen on the columella. This shell is rare. 



Genus TURBONILLA, Leach 



Shell minute, awl-shaped, its many whorls crossed by sharp, 

 close ridges, columella straight, outer lip thin, simple. 



A very large genus of very small pyramid shells, widely 

 distributed, chiefly in warm seas. 



The Short Pyramid Shell {T. curta, Dall) is a Cerithium 

 in form, but its daintily cross-ridged spire is but one-third of 

 an inch long. 



Habitat. — Cape Hatteras southward. 



The Chestnut Turbonilla (T. castanea, Cpr.), with the 



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