The Oyster Drill 



orous "snails." Through this hole the soft parts are sucked; the 

 solid flesh may be picked at leisure from between the gaping valves. 



At intervals the oysterman drags his " tangle," a great mop 

 made of untwisted rope fibre, and his dredge over the oyster 

 beds, and destroys all the drills caught up by them. These are 

 not effectual exterminators by any means; but they are the best 

 things yet devised to combat the enemy. The creature's small 

 size, its rapid multiplication and its ravages when present in 

 numbers make continuous warfare upon it the only salvation 

 for the oyster beds. 



Chesapeake Bay was probably the original home of the 

 drill. From this locality it has migrated north and south; trans- 

 planted with the oysters to San Francisco Bay, it has spread 

 also on the west coast. 



Each female lays during a period of several weeks a total 

 of ten to one hundred egg cases. Each one is vase-shaped, 

 vertically flattened and keeled, of clear, parchment-like mem- 

 brane, containing about a dozen eggs. The cases are attached 

 by broad foot-like bases in regular rows, forming patches on the 

 under sides of overhanging rocks, or other support, just above 

 low water mark. 



The Florida Drill {U. Floridana, Conr.) differs from the 

 Atlantic species in having shouldered whorls, the ribs forming 

 knob-like projections at the angles. The ashy surface is not 

 banded. Aperture, purplish. Length, \\ inches. 



The Mexican Drill {U. Mexicana, Rve.) has its nodulous 

 sculpture yellowish on a chocolate ground. It is less than an 

 inch long, and resembles U. Floridana. 



THE EUPLEURAS 

 Genus EUPLEURA, H. and A. Ads. 



Shell ranelliform, with two prominent, and intermediate 

 smaller varices ; aperture toothed within. Five species. Distribu- 

 tion, West Indies, Atlantic coast of United States and Panama. 



This confusing genus has the shell of a Urosalpinx, the teeth of 

 a Murex, the varices of a Ranella, and the operculum of a Purpura. 

 Tryon considers it intermediate between Murex and Ranella. 



E. caudata, Say, is the type. The shell is white to dark 

 brown, reddish brown within. There are five whorls, each shoul- 



39 



