NATURAL SCIENCES OF PHILADELPHIA. 347 



Measurements of four specimens as follows : 



Habitat. Rock}' Point, Tampa Bay, West Coast of Florida, 

 where I collected four living specimens from off the underside of 

 clumps of oysters ; also at other points along the shores of said 

 bay and the adjacent keys, by Col. E. Jewett, who obtained many 

 specimens. It is perhaps the most common of the pleurotomoid 

 forms of the above region. 



