92 
Xatural lHst07'y Society of JSf. JB., Bulletin N~o. IV. 
ctllms) are abundant in the large tide pool on Pendleton’s Island, 
clinging to the rocks and to one another. As a general rule these 
are only obtained either by dredging or from the stomachs of fishes, 
but here they can be seen and studied as they actually live. This 
imol, to whicli I refer so frequently, teems with animal life, and a 
most interesting paper could be written upon its inhabitants alone. 
Common everywhere on muddy bottoms is the trumpet-sliaped 
Bntalis striolata.^ and common everywhere in tlie littoral zone is the 
common lim})et ( Tectura testudinalis) . The latter seems to attain a 
larger size here than elsewhere, for Dr. Gould says that the largest 
specimens he ever saw were 1 1-4 inches long, while I have collected 
them more than 1 1-2 inches in length. Perhaps the only one of tlie 
marine Gasteropods occurring in the Bay, that is eaten by civilized 
man, is the periwinkle {Littorina Uttorea). It is very abundant 
between high and low water mark, clinging to the rocks and seaweed, 
and seems to require to be exposed to tlie air for a certain length of 
time every day, as it is never dredged from deep water. Tliis latter 
peculiarity is common to it togetlier with several species, such as 
the purple sliell, the limpet and others. The large round whelk 
{lunatia heros) is found in many places, but most abundantly at 
Minister’s Island, while lunatia triseriata^ formerly regarded as the 
young of lunatia heros., is abundant among the shells of clams at 
several jioints. As the identity of L. triseriata with the young of 
X. heros is still a matter of dispute, the following facts, which seem 
to prove them to be distinct species, though closely allied, may be of 
interest. 
(1) . Specimens distinctly marked with the three dark lines of X. 
triseriata are found of far greater size than others of similar shape 
without the markings, which could hardly be the case were the 
former the young of X. heros. 
(2) . X. triseriata is found in large numbers burrowing in the sand 
among clams and lob-worms. While I have never found any speci- 
mens without the tliree lines in that situation, I have found them on 
the beach at low water mark, whicli would seem to indicate that 
burrowing in the sand is the proper habitat of triseriata., which is 
thus distinct from the unmarked shells, which are, without doubt, 
the young of X. heros. 
Of the family Purpuridye the purple shell {^Purpura lapillus) 
from which was obtained the much valued “ Tyrian purple ” of the 
