The Oyster Drill 



dark-coloured. This genus is distributed chiefly in cold waters. 

 One group is Arctic, another Antartic. Species, forty. 



T. clathratus, Linn., is a variable species, distributed from 

 the Arctic Seas to Vancouver's Island, Massachusetts, Iceland, 

 Great Britain and Norway. British forms are small, ^ inch long, 

 with about twenty ridges on the body whorl. The American 

 forms are larger in many regions, and they vary in number of 

 ribs. Doubtless they are varieties of the same species. 1 he Ice- 

 landers call this mollusk "St. Peter's Snail." 



T. muriciformis, Dall, found on the Alaskan coast, is almost 

 exactly a miniature Fulgur canaliculatus in shape. It is over 

 two inches long. It is closely related to the preceding species. 



The Three-cornered Trophon {T. triangulatus, Cpr.) is 

 large but very thin, and light of weight. Its outline is triangular; 

 the tapering stem slopes downward from the extremities of the 

 spreading wings of the body whorl. These are numerous and so 

 high as to overtop the elevated spire. The colour is a soft "Quaker 

 drab," or reddish brown; the small, round aperture is lined with 

 white. Though an occasional specimen is washed ashore near 

 San Pedro or at Santa Catalina Island, it is so broken as to be 

 almost valueless. The perfect ones are dredged in deep water. 

 Their exquisite form and colouring repay the hard work it costs 

 to get them. They are among the rare and lovely treasures of 

 the deep. Length, 4 to 5 inches. Southern California. 



Belcher's Trophon {T. Belcheri, Hds.) is known among Cal- 

 ifornia collectors 2iS Chorus Belcher i,Wds. It is broadly pear-shaped, 

 four to six inches in length, its base a short, open canal. The 

 colourless surface is dull and tinged with brown. The spire is 

 elevated, the whorls distinctly angled at the shoulder, and con- 

 tracted to deep sutures between. Crossing the whorls are many 

 laminated varices. The lip is thin, and drawn out into a fold 

 at the outer, widest part. This, closing into a hollow tube as 

 growth proceeds, forms a coronal of curved horns around the 

 spire. There is a large tooth on the lower margin of the outer 

 lip. The columella is narrow and rolled back above a deep um- 

 bilicus. Shells of this mollusk are picked up occasionally at low 

 tide from San Diego to San Pedro. It is also found in Japan. 

 Its place among the genera of Muricidie is uncertain; it has the 

 operculum of Purpura, the tooth of Monocerus, the varices and 

 canal of Trophon. Its dentition is like that of the Buccinidae. 



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