BIOLOGY OF ACMA TESTUDINALIS MULLER. 
M. A. WILLCOX. 
Acmea testudinalis Müller, the tortoise-shell limpet, as it is 
called by Forbes and Hanley, is the common limpet of our New 
England shores. It, together with its variety alveus, is the sole 
representative on this coast not only of its genus and family but 
of the entire group of the Docoglossa and by far the most con- 
venient example of the suborder Diotocardia, which includes all 
the more primitive Gasteropods. It is abundant and accessible, 
itis easily kept alive in aquaria, and living as it often does in 
tide-pools, is conveniently observed under its natural conditions. 
But in spite of these facts it has never been made the subject 
of careful study. 
I am at present engaged upon a paper which is intended to 
supply this lack and from which I excerpt the following biologi- 
cal notes. 
Acmeea is a large genus whose eighty-four species are widely 
scattered over both northern and southern hemispheres. Repre- 
sentatives have been recorded not only from both eastern and 
western shores of all the great continents except Africa,! but 
from Australia, from New Zealand, and from many islands of the 
Atlantic and Pacific including some which are oceanic. The 
genus is at present arranged only tentatively. “More than any 
other shells, these must be studied with constant reference to 
not only habitat geographically, but station as well. For an 
exact knowledge of the group we must therefore wait until 
observations on the species are made with special reference to 
their modes of life and surroundings" (Pilsbry). It seems 
probable, moreover, that a careful comparative study of the dif- 
ferent species might throw light upon various questions of 
geographical distribution. This statement of the final aim of 
! Two species only are as yet recorded from this continent: one from Natai 
and one from Cape Town. 
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