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merous genus, naturally associated, and well character- 

 ized. Bruguiere reduced it to such shells as had per- 

 manent, thickened bands or varices ; which arrange- 

 ment rejected the genera Fasciolaria, Fusus, Pyrula, &c. 

 Lamarck however, on consideration, has been induced 

 to form two other genera, the G. Ranella and the G. 

 Triton, each exhibiting a great variety of species, 

 differing from the G. Murex, which, as it is now con- 

 stituted, comprehends only such shells as have three 

 or more varices on each whorl: and it is custom- 

 ary, when speaking of the number of varices, to 

 count only those on the lower whorl. It may be 

 remarked that these varices or bands are arranged 

 obliquely in succession on each whorl, forming longi- 

 tudinal rows, becoming more oblique near the sum- 

 mit of the spire. 



The Murices are easily recognized by their hav- 

 ing three or more rows of varices on each whorl. 

 In the Ranellae there are only two, arranged on 

 either side in rows; and the Struthiolariae have 

 only one at the margin. It is therefore evident that 

 the animal of the Murex adds, at each increase, a 

 smaller portion to the size of its shell, than those of 

 the other genera mentioned. Shell oval or oblong, 



