GASTEROPODS 383 



which cross the whorls, projecting almost one fourth of an inch from the 

 body of the shell. Between each of these varices is a large node. There 

 is, besides all this, a system of pronounced revolving ribs which cross 

 the varices and nodes, giving to the shell a greatly roughened appear- 

 ance. The interior is bluish-white. The operculum is corneous, with a 

 subtenninal nucleus. Unfortunately, this really handsome shell is usually 

 incrusted with coralline or calcareous matter, which must be removed 

 with acid before a good idea of its appearance can be had. In color it i- 

 reddish-brown to dark chestnut on the varices. It is very common on 

 the west coast of Florida, but rarer elsewhere. (Plate LXXIL) 



M. potmim. A more abundant species, found all along the coast 

 from Hatteras to Texas. It is not so elongated as the last, and its sculp- 

 tural design is much less exaggerated. Between each of the varices are 

 two nodules. The aperture is oblong-ovate, and the anterior canal is 

 nearly closed and recurved toward the back. Revolving ribs cross the 

 varices and nodules. The color is ashen, with chestnut tips upon the 

 nodes and varices, and chestnut-colored patches about the aperture. The 

 varices are simple and not foliaceous as in M. rufus ; the shell is more 

 globose. Length two to three inches. (Plate LXXII.) 



M. (PhyUonotus)fulvescens. The largest of the American murices. 

 It is not commonly found except in Texas. 



GENUS Trophon 



T. clathratus. A fairly common shell of the Maine coast; 

 although it belongs to a deeper zone than that of the tides, it is 

 occasionally found after storms upon the shore. It is a small 

 fusiform shell, with many prominent longitudinal ribs and a 

 produced anterior canal. Trophon is a boreal genus, which finds 

 the best conditions for life in the icy waters of Labrador and 

 Greenland. 



GENUS Urosalpinoc 



The genus Urosdlpinx is closely allied to Murex and Trophon. 

 Several of its species are found on the east coast of the United 

 States. 



U. cinerea. This well-known species is regarded by 

 Chesapeake and Long Island Sound oystermen much in the 

 light of a plague. These active predaceous mollusks live 

 upon bivalves, and preferably upon oysters. They bore a 

 small round hole through the shell of their helpless victims, 

 and then proceed to extract the succulent, fleshy animal 

 from within. The oystermen call them by the suggestive 

 name of " drill," and wage incessant warfare upon them. 

 In some years these mollusks appear to go into partnership 

 with the large starfish, Asterias, and the combination of the 

 tw . can soon destroy any oyster-bed. The original home of 

 this destructive little creature is presumed to be in Chesa- 



