NATURAL SCIENCES OF PHILADELPHIA. 341 



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 

 ba}' 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. 



