32 



THE PURPLES. 



they all belong to one species. The Atlantic Purple 

 exhibits similar varieties of form and color. 



Purpura lima^ Mart., li^-ma, which is the same as 

 Purpura canaliculata^ Duclos, is shown 

 in Fig. 12. It is more rarely met with 

 than the last species, probably on ac- 

 count of its living in deeper water. In 

 size it is rather larger than P. saxicola^ 

 while in appearance its shell is more 

 smooth and symmetrical. The spire 

 consists of four whorls, separated by 

 distinct sutures. The distinguishing 

 Fig. 12. feature, however, and the one which 



gives the name to the shell, is the presence of about 

 fifteen spiral grooves on the whorls, giving its surface 

 somewhat the appearance of a coarse file. The oper- 

 culum, as in all the Purples, is thin, horny, and some- 

 what oval in shape. The color of the shell is light 

 brown. It is a ver>^ pretty species, and may easily be 

 recognized by its rounded and channelled whorls. 

 There is another member of the same genus which 

 lives in San Francisco Bay, but which 

 is more common and more finely devel- 

 oped, a few hundred miles farther north- 

 ward. The shell varies \^rw much in 

 respect to its surface, a specimen being 

 represented in Fig. 13, which is only 

 moderately rough. You notice that 

 the shell is widest in the middle, that 

 it has an elliptical aperture, a short 

 canal, a distinct spire, and numerous 

 sharp varices. Its color varies from 

 white to brown; some specimens are pure white and 

 are quite smooth, others are almost wholly brown 



