146 Marine Shells of the Western Coast of Florida 



suture; a rounded notch near base and a deep recurved, basal notch; 

 interior polished, beautifully colored in shades of orange, salmon- 

 pink, purple and brown; columellar callus polished, reflected over 

 front of body whorl. 



Strombus pugilis alatus Gmelin is the most common large gas- 

 teropod on the sand bars and tidal flats about Sanibel Island, Flor- 

 ida. Normal depth range in this locality seems to be from low tide 

 mark to two or three fathoms. Dredging operations off Sanibel Island 

 in depths greater than three fathoms yield only an occasional in- 

 dividual Strovilms during the fall and winter, but in March of 1938 

 and 1939, great numbers of S. pugilis alatus were taken in five to 

 seven fathoms of water, six to ten miles off shore. For half a dozen 

 hauls, the dredge came in filled with these moUusks alone. Pro- 

 digious numbers must have assembled in restricted localities where 

 conditions were congenial to them, as the experience was repeated 

 at various places over a considerable area. All were taken on sandy 

 and gravelly bottom in company with sea urchins, sand dollars, and 

 but few other mollusks. 



Most of the Strombus were adult, and from the posterior notch 

 tangled masses of thin cordlike threads, covered with adherent 

 grains of sand and small bits of broken shell hung, seemingly at- 

 tached to the mollusk. These threads were extruded through the 

 posterior sinus in masses equal to a tablespoonful. The animals were 

 all withdrawn into the shells when captured, but m each observed 

 case, the egg mass was attached to the mollusk and required some 

 force, for withdrawal. Some of the shells were infested with the 

 boring sponge, Cliona, but the infestation must have been recent as 

 the borings were scattered and superficial. 



Occasional specimens of fresh juvenile and adult shells of 

 Strombus costatus inermis are found on the Gulf beaches of Captiva 

 and Sanibel Islands, also infrequent worn specimens of Strombus 

 gigas. 



Family OVULIDAE 



The mollusks of this family resemble and are closely akin to 

 the animals of the Cypraeidae. 



The shells are ovoid or fusiform, with a straight linear opening, 

 canaliculated at each extremity of the shell. 



