110 
MONOGRAPH OF THE GENUS STROPHIA. 
formerly fortified, as the remains of old ramparts testify, and although 
now it is seldom visited, there must have been constant communication 
between it and the main island in former times. It was then doubtless 
that Strophia eurtissii was introduced. Since then it has changed 
considerably. In fact, it has become one of the most interesting 
forms of the genus that I have seen. The form and color does not 
differ exceedingly from those of the type, but the size is somewhat 
smaller (.87 by .40). The margin is pushed forward almost to the 
outer diameter of the shell (in some specimens beyond this), and has 
become very thin. But the most important feature is the tooth, which 
is at least three times as long as high. (See Fig. 34 a, where I give a 
cut of this tooth, side and top view, and compare with ib. b, where is 
given a view of the type, S. eurtissii). The striations are quite regular 
and arranged in lines. 
Were if not for the fact that not every specimen on 
Key has the tooth elongated to the extent shown in the type, I should 
not hesitate to consider this well-marked form as a species. I have 
elsewhere shown that on wind-swept islands, like the Caymans, species 
of Strophia have elongated teeth, in order that the animal may have, 
better control over its shell, as it has no muscular attachment to it ; and 
here on this little key, lying as it does in the middle of the harbor, the 
form I have just described, has, through the progress of evolution, 
acquired a similar tooth to those which characterize the Cayman 
Strophias. 
Young specimens of Strophia eurtissii have the central tooth 
missing, hut with the upper well developed. There are, however, no 
other teeth whatever, as is usual in some other species. 
Known from the closely-allied S. thorndikei by the larger size, 
less creamy color and thicker margin to the aperture. 
From other of the short-toothed Strophias which occur on New 
Providence and in its vicinity, in which the central tooth is only twice 
as long as high, this species may 'be distinguished by the fleckings, 
combined with usual absence of the upper tooth. Occasionally this 
is present, but is then very minute but oftener the prominence given in 
the type Is not even seen. 
I have named this beautiful Strophia for my friend Mr. George F. 
Curtiss, to whom I am not only indebted for many acts of kindness 
when he was with me, but also for ready sympathy and encourage- 
ment in all my pursuits. 
This common Strophia has" found its way into collections under the 
Spotter’s 
aeaa i 
