THE SMALLER SEA-SHELLS 179 



are needed links in the great chain that binds earth 

 to heaven. 



As already explained the name 'Purpura is now 

 applied to certain members of the Murex family- 

 The familiar shells that formerly bore that name 

 are now called l^hais^ a name given by Bolten in 

 1798. While this will be the Latin name, there is 

 no objection to calling them Purple-shells as before. 



Most of our Purples prefer to live where they will 

 get frequent changes, for we find them selecting as 

 a home those rocks that are alternately left bare and 

 then covered again by the tide. They are car- 

 niverous creatures, and like the Oyster Drill they 

 can bore through the thin shells of bivalve mollusks, 

 and then devour the poor inhabitants. We have but 

 few species on this coast, but some of those furnish 

 very numerous specimens. The first and most com- 

 mon kind is named l^hais saxicola^ Val., the Rock 

 Purple, {Purpura saxicola), Figure 168. Though 

 the cut is larger than the average ^^ 



shell, specimens are sometimes found ^7^^ 

 that fully equal it in size. The shells ^^^^^m 

 diifer much in details, even in speci- ^^^^^^m^ 

 mens living near each other, and it is ^^^&^^^ 

 no wonder that many diiferent names ^S^I^Hil) 

 have been given to the varieties. In W Bf V 

 general the spire is short, the colum- ^Sgy^ 

 ella flattened, the outer lip thin, the pjg ^gg ^3 

 aperture large, and the interior of the 

 shell of a chestnut color. Sometimes the outside is 

 smooth and almost black, sometimes the shell is light 

 colored and coronated, but often it is of a dingy 



