152 Marine Shells of the Western Coast of Florida 



as a knife. Bivalve prey is gripped by the powerful foot and the 

 shell margin pressed against the spine until it is driven like a 

 wedge between the two valves, forcing them apart. 



The Muricidae possess a special glandular structure whose se- 

 cretion affords a royal shade of purple when appropriately treated. 

 This property of the Muricidae was known to early races of the 

 Mediterranean people, who made from certain of these moUusks 

 the Tyrian purple dye. 



The shells of this group of mollusks are thick and solid, with 

 moderate spires terminating in sharp apices. The body whorls are 

 relatively large and the round, or rounded apertures are produced 

 into straight, partly closed canals or notches; no posterior cord 

 or notch is present. The shell surface is rough, and usually bears 

 longitudinal rows of more or less tuberculate or spiny protuberances, 

 useful as protection against fish and other predatory enemies. 



Genus MUREX Linne, 1758 

 Murex-7« cabrltii Bernard! PI. 30, fig. 211 



Alt., 50-55 mm. Smooth, thin periostracum. Unicolor, flesh or 

 deeper pink; spire of four and a half convex whorls, nucleus minute; 

 body whorl rounded; aperture prolonged into straight, partly closed 

 anterior canal more than half the height of shell; sculpture of three 

 equidistant strong axial ribs bearing sharp spinous processes; be- 

 tween these ribs are low rounded ribs; revolving channels render ribs 

 slightly nodulous; sutures distinct; aperture oval, outer lip crenu- 

 late; columellar callus continuous with canal wall; two rows of sharp 

 spines, usually six, on canal; operculum light brown, corneous. The 

 delicate spinous processes may be partially developed or absent. In 

 beach specimens they are usually broken. Beautiful and perfect speci- 

 mens are taken by the divers of the Tarpon Springs sponge fleet. 

 Fresh shells have been found on Sanibel beaches and living speci- 

 mens dredged off Marco, and Destin, Florida. 



Depth range 25 to 164 fathoms. 



Mnrex recurvirostris rubidus-" F. C. Baker PI. 30, fig. 212 



Alt., 30 mm. to 50 mm. General characters of shell similar 



to those of M. cabritii; spire acute and slightly more extended; 



-^^ Lat, murex, the purple shellfish. 



=^^^ Lat., recurvirostris, curved beak; ruhidus, red. 



