The Purples. Dog \A^inkles 



The Rock Purple (P. saxicola, Val.) is as abundant on the 

 CaHfornia coast as its near relative, P. lapillus, is on the coast of 

 New England. It exhibits as great a tendency to vary. The 

 shell is thicker, with a smaller aperture. Specimens reach one 

 and a half inches in length, but the average specimen is less 

 than an inch long. The dingy exterior is marked with double 

 spiral bands of brown. The lip is sharp; the columella twisted 

 and flattened; the spire short. 



Habitat. — California. 



The Grooved Purple (P. lima, Mart.) lives in deeper water, 

 so is more rare than the last species. It has an elevated spire of 

 four rounded whorls separated by deep sutures. Fifteen spiral 

 grooves sculpture the surface uniformly. Colour, light brown. 

 Length, \ to i inch. 



Habitat. — California. 



The Wrinkled Purple (P. crispata, Chemn.) ranges north- 

 ward from San Francisco Bay to Alaska. The species improves 

 as it moves to higher latitudes. Specimens from Puget Sound are 

 two inches long, with longitudinal frills and spirally banded with 

 rich brown. Smoother specimens, of duller hue and smaller size 

 occur southward. The white aperture is smaller; the lip is 

 toothed within. 



THE CASTOR BEAN SHELLS 

 Genus RICINULA, Lam. 



Shell ovate, solid, usually with spiny processes on the numer- 

 ous varices; aperture long, narrow, toothed; canal short, oblique; 

 columella wrinkled; operculum horny, thin, semi-lunar. Includes 

 thirty species, inhabiting coral reefs among Polynesian Islands. 



This genus, much like Purpura, contains also a sub-genus 

 named "mulberry shells." The compact shape and spiny or 

 lumpy surface give reasonableness to the common name. 



The Bristly Castor Bean Shell (R. horrida, Lam.) is stud- 

 ded with stout black tubercles on a white ground. The flaring 

 outer lip and the exceptionally wide columella are tinged with 

 violet. The lip bears strong inner teeth; the columella, cross 

 folds below the middle. Length, i to if inches. 



Habitat. — Hawaiian Islands, Philippine Islands. 



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