The species is reported as common along the Atlantic Coastal Plain in 

 Pleistocene deposits approximately one million years old and in a range similar 

 to that of modern descendants (Richards, pers , oom ; Shimer & Shrock, 1944), 

 Specifically it has been collected in marine -deposits in Point Shirley and Nan- 

 tucket, Massachusetts, and on Gardiners Island, New York (Verriil & Smith, 1874); 

 in Barnegat, Beach Arlington, Peermont, Holliday Beach, Two Mile Beach, Cape May 

 and Heislerville, New Jersey (Richards, 1933; 1944); in the coastal terraces of 

 the Pamlico formation amosag marine fossils in Maryland, Virginia, North Carolina, 

 and South Carolina, bat not in Delaware (Richards, 1936); in the northeastern two- 

 thirds of the coast and the mid-ceittral west coast of Florida, but not on the 

 southern or northwestern porttoas of this atate (Richards, 1938); and in one 

 locality in Louisiana, but not m Alabama, Mississippi, or Texas (Richards, 1939), 



More recently U . cimerea was discovered in company with oyster shells 

 in sediments of the Charles River estuary, Massachusetts, in excavated layers 

 approximately 3, 000 years old (F. Johnson, 1942). 



Recent Vertical Distribution 



Within its geographic limits the oyster drill occupies a relatively 

 broad vertical range,, extending in favorable salinities from the mid intertidal 

 zone to unknown depths in the sea, Tryon (1873-74) reports its presence in 

 maximum depths of 90 feet; Verriil and Smith (1874) and C Johnson (1915), in 48 

 feet; and Dall (1889), in 60 feet. Chestnut (pers , com.) recently extended this 

 range when he dredged a few specimens on the edge of the Gulf Stream, off Cape 

 Lookout North Carolina, in 120 feet of water, and observed evidence of drilling 

 on bivalves accompanying the drills As additional fauna! studies are made in 

 deeper water off our coastal areas the bathymetric range of the drill may well be 

 extended . 



Recent Horizontal Distribution 

 General 



So far as the incomplete paleontological evidence discloses U. cinerea 

 evolved somewhere along the middle Atlantic coast of the United States, and, 

 before the Age of Man, spread intermittently over the range between Florida and 

 Massachusetts . This dispersal probably occurred at an unhurried rate proportion- 

 ate, for the most part, to the sluggish locomotory behavior of the drill, and was 

 abetted by the high degree of adaptability of the snail, the availability of transport- 

 ing agents, and by accessibility of routes for movement to suitable new environments , 

 Amelioration of physical, chemical, and biotic ecological factors previously obstruct- 

 ing its dispersion undoubtedly further fostered its distribution. 



