268 Marine Shells of Massachusetts. 
plish white surface, also in -a few from Nantucket and 
in many from. New Bedford. 
Length one inch ; breadth .55 en 
This species inhabits not only our estuaries, but our 
ocean shores. It seems, however, to prefer situations 
where it is not exposed to the surf of the open sea. 
The finest specimens which I have seen, were growing 
at Nantucket, where they are as abundant as in any of 
our harbors on the continent. Kiener, who deseribes 
the species from the young, under the name of B. olivi- 
_ forme, observes that his specimens were sent from New 
York, habitat unknown; but from the appearance of 
the shell, which is usually carious upon the upper 
whorls, presumes that it inhabits: fresh water. Any 
one who sees the shell is not surprised at this conjec- 
ture. Indeed it does grow in places where there is 
some admixture of fresh ‘water, at the margins of our 
marshes ; but this is so far from being essential, that, as 
already remarked, its fullest detelopsdt is in situations 
where no fresh water is present. 
No species, of n size, is so binis on our 
shores. 
In Boston harbor I have obied tht in winter, 
these animals collect together in heaps, filling up slight 
: nc on the flats, but. ipn during warm 
Purpura. 
Pp tpl Law., An. sans "Van Büccinum n lapillus; 
a 
