THE NAUTILUS. 57 



PURPURA LAPILLUS L. 



(Extract from the report of Mrs. D. J. Wentworth. From the Transactions of the 

 Isaac Lea Chapter for 1896.) 



No shell is more common on our New England shores than Pur- 

 pura lapillus Linne, and yet, no shell of this region has to me, at 

 least, so much of interest connected with it. 



Purpura lapillu* is an humble but most worthy descendant of the 

 aristocratic Muricidse, and surely the Murex is an aristocrat among 

 shells, with its beautiful forms, dainty sculpturing, delicate coloring, 

 and its long traditions of usefulness and importance. 



Plain in its general aspect, as it certainly is, Purpura lapillus has 

 nevertheless, much in common with its more highly favored rela- 

 tions. It is an old member of an ancient race, fossil remains of 

 Purpura lapillus are found in the Red Crag deposits of Europe. 



This species is remarkable for its variation in solidity of shell, 

 form, sculpture size, coloring and habitat. It varies in thickness 

 from three-sixteenths of an inch to a shell so thin one could easily 

 perforate the outer lip with a pin. In form they vary from a short 

 broad shell with obtuse spire and flattened whorls to a long shell 

 with acute spire and convex whorls, 



In some the coarse revolving ridges are barely discernable, while 

 in others they are very prominent. The faint lines of growth which 

 intersect the revolving ridges of this shell are, in some specimens, 

 brought into marked prominence by rows of ruffles or scallops, and 

 this sculpturing undoubtedly gave Lamarck reason for naming this 

 variety Purpura umbilicata. Many of the solid shells have rows of 

 nodules or teeth within the aperture on the outer lip, 



These solid shells are usually grayish-white or white outside, with 

 reddish-purple, yellow or white apertures ; but the thinner shells are 

 often brown, orange or lavender, and these colors are frequently 

 banded with white. I have never seen two specimens banded just 

 alike. The orange and white combinations are especially pretty. 

 The variety called by Lamarck P. umbilicata, so far as I have ob- 

 served, are always a greyish-white on the outside, with a reddish- 

 purple aperture. This variety I have found only in a brackish 

 river where they are often seen crawling about in the mud, and their 

 color is so nearly the color of the mud on which they are found that 

 it undoubtedly serves to protect them from the ravages of their 

 enemy. Associated in this river with Purpura lapillus, and much 

 resembling it in size, color and general shape, is the Urosalpin.c 

 cinerea. The usual habitat of the Purpura is in the nooks and 

 crevices of rocks. Why do these river shells choose the mud? 



