MONOGRAPH OF T1IE GENUS STROPHIA. 
155 
large, is placed low, not once its width from the floor of the cavity. 
Margin, not produced forward quite as far as the diameter of the 
shell, is a little thicker than the shell behind it, is slightly beveled into 
a blunt edge, but this is not produced backward. The frontal bar is 
not very well developed, although it completely crosses the aperture, 
yet the striations are indicated within it. 
Color of shell, reddish brown, externally, with the striations paler. 
Pale brown internally, becoming paler on the teeth and magrin. 
DIMENSIONS. 
Size of type, .85 by .40. Largest specimen, LOO by .43 ; 
smallest, .72 by .35. Longest specimen, 1.00; shortest, .72. Greatest 
diameter, .43 ; smallest, .35. 
OBSERVATIONS. 
Individual variation is toward a form with a thickened margin, 
that is beveled and grooved, in this respect resembling the margin of 
a fossil form (S. agassizi) recently described by Dali (Bulletin Mus. 
Comp. Zool. Vol. XXV, 1894, p. 122) as coming from the aeolian 
limestone, of the top of the quarry, about a mile east of Ft. Charlotte. 
While S. agassizi may be the remote ancestor of this species, it is 
probable that it has passed through several species since then. S 
agassizi has no striations, but 1 have found a large fossil Strophia 
scattered through the aeolian limestone of the surface of New Provi- 
dence, in the neighborhood of Nassau, which is more probably the 
immediate ancestor of S. carlotta. Individual variation is also toward 
producing a form with coarser, more widely-apart, striations. Indivi- 
duals of this kind were doubtless the origin of S, neglecta, for S. 
neglecta, although such a strongly marked species, has some characters 
in common with S. caulotta, such as general form, wide, low aperture, 
nine whirls, and the peculiar form of the striations, which in S. 
carlotta are, as nearly as possible, half pillars, recalling at once the 
beautifully-polished striations of S. albea from Spruce Key. Those 
striations appear of the same general form in neglecta and through it 
in S. n. agava, but they are broken and somewhat roughened in S. 
neglecta. They have, however, in a measure, regained their original 
form in S. n. agava. Besides these individual variations, we find two 
well-marked forms. 
No. 1. A dwarf form, the smallest given in Dimensions. Whirls, 
eight, and striations, eighteen to the first whirl, otherwise the same 
as in the type. 
