MARINE UNIVALVES 



151 



has a regular, conical spire, three inches long, marked 

 with numerous rounded knobs, which are often over- 

 grown and partially concealed by a stony crust, 

 which was once the home and protection of numerous 

 little sea animals. The aperture is pear-shaped, and 

 the outer lip has many small teeth and internal 

 ridges, while the canal turns backward. The umbili- 

 cus is large and distinct, while the operculum is dark 

 and conspicuous. This shell is found chiefly in 

 southern waters. 



Figure 129 gives a view of 

 Clir y s o d o mu s pli oeniceus^ 

 Dall, the Purple Chrysodome. 

 Its seven whorls are of a pur- 

 plish brown color. The sculp- 

 turing is feeble, and the epi- 

 dermis conforms to the lines of 



Fig. 129 (*) 



growth. It was dredged off 

 British Columbia in 238 

 fathoms of water. 



Chrysodo7Jius mag nus, 

 Dall, the Great Chryso- 

 dome, Figure 130, grows to 

 a length of three inches. 



Fig. 130. X % (*) 



