This species as a whole is distinguished from Marginella redfieldii Tryon, by its more flexuous and callous outer lip and wider aperture; from M. torticula, by its greater width and straight axis; from the Volvarina group, by the higher spire and posteriorly angulated outer lip. The deep-water form is larger and less pellucid than those found in shallow water, but hardly distinct enough to retain a separate name. Mr. Tryon unites this with nitida Hinds, described in 1844 without locality. I confess myself unable to see the exact correspondence between them which he mentions, even by his own figures. The color and form seem to me quite as different as in any two valid species of the same group. If nitida is to supplant a later name, it would seem that Marginella paxillus Reeve is much more like M. nitida than is Conrad's species. The species described by Hinds is of a deep brown, like the dark varieties of M. opalina Stearns. In looking over a great many specimens which have come to me, I have never seen a specimen of M. succinea of this color, though, knowing how variable this section of the genus is in its coloration, there seems to be no reason why it should not occasionally be of a dark color.

This species, which I was led to think a possible deep-water race of Marginella avena, is found more or less abundantly in shallow water in South and West Florida. Specimens have been compared with Conrad's type, by the kindness of Mr. G. W. Tryon, Jr., at the Academy of Natural Sciences, Philadelphia. Conrad's species has never been figured in a satisfactory manner. The figure we give represents, considerably enlarged, a rather blunt-tipped deep-water specimen. They vary somewhat in the height and acuteness of the spire. The color is usually light fawn or amber of the yellow shade, or a mixture of the two without color pattern. I have from Florida some small pure white specimens which are only differentiated by color and size from the typical form, though the absence of color gives them quite a distinct aspect.

Caribbic area.