MONOGRAPH OF THE GENUS STROPHIA. 
177 
and this sub-species gave rise, most strangely, to the little dwarf, S. 
restricta. The most sceptical regarding the value of color as a specific 
character has only to visit this key and note the transition of S. 
pilsbryi into its sub-specific form, with its accompanying correlative 
characters, while the little S. restricta exhibits clearly how closely one 
species may live to another and yet be distinct. The sand from which 
grew the tree and bushes on which I found S. restricta isolated this 
form as completely, if not more so, than if miles of ocean rolled 
between them. 
I have said under the Habits of Strophia nana (Vol. I Contribu- 
tions, page 28) that this Strophia had the most limited distribution of 
any animal with which I was acquainted, but in this respect it must 
yield the palm to S. restricta, for this species was confined to a single 
tree and the bushes that came indirect contact with it, in fact, all of 
the specimens which I collected I gathered without moving a single 
step. 
53 STROPHIA EXliVfEA Novo. 
Choice Strophia. 
Fig, 59. A, front, B, side view of type. 
DESCRIPTION. 
Sp. Cii. Size, medium. Shell, not very thick. Striations, 
present, but very fine. Whirls, ten. Examined 1,000. 
[Note. This species and the next following belong to a peculiar 
group of Strophias, which may, with perfect propriety, be placed in a 
separate sub-genus which may be characterized as follows : 
6. MULT 0 ST RO PH I A. 
Central tooth, slight, not thicker than high, striations, 
numerous, exceedingly fine and polished. Type, Strophia eximea 
Mayn. Locality, Bahamas.] 
Form of shell, cylindrical, with the first three whirls equal in 
diameter, then the shell slopes gradually to a blunt point, forming 
an angle of sixty-five degrees. The striations are very numerous, fifty 
to the first whirl, they are rounded, regular, being half cylinders, and 
they are very slightly inclined from right to left. 
Aperture, large and open. Lower tooth, small, .03 high, thinner 
than high, but about three times as long as high, is set very far 
