The septate shell is oblong, the sides being nearly parallel, but slightly expanding anteriorly, the right slightly convex and the left slightly concave; the posterior margin is regularly rounded; the anterior more broadly rounded; the apex depressed, bluntly rounded, excentric, reaching nearly to the right margin, smooth except for slight concentric wrinkles, lines of growth fine and regular; the anterior slope is slightly convex; the very short posterior slope below the projecting apex to the line of the septum is straight and oblique; the right lateral slope is steep and nearly straight, the left slope very convex; the septum is very short, being less than half of the length of the septate shell, convex on its lower surface, the margin is very short, being less than half of the length of the septate shell, convex on its lower surface, the margin is very concave and on the right side, extends further forward than it does on left, there does not seem to be the distinct thickening of the margin so noticeable in other species; aperture much larger than in any other species yet described. Length 2; width 1.5; alt. .75 mm. Type (43455 Coll. Walker) from the Maya Farm, Quirigua, Guatemala, collected by A. A. Hinkley. Cotypes in the collection of Mr. Hinkley. This fine species is the first from either Central or South America, of which both the septate and adult forms are known. It differs from all other described species except _crepidulina_ Guppy in the small size of the septum and the consequent difference in the position of the aperture of the septate stage in the adult shell. The septum in the specimen figured appears very like the incomplete septum in the North American species, but as the three adult specimens before me are exactly alike in the position of the septate shell, this would seem to be the normal condition in this species. The specimen figured, which is 3.25 mm. in length, has apparently slightly passed the septate stage and begun the growth of the constricted portion of the adult shell and shows the beginnings of the radial striæ. With the Gundlachias was associated a species of _Lævapex_, very like the _excentricus_ Morelet. Whether it has any closer relations with the _Gundlachia_ remains to be determined as the radula has not yet been examined. While the general aspect of the two species, if such they be, is very similar, the _Lævapex_ has a very much more acute apex than the _Gundlachia_. As shown by the figure, the radula of this species is quite typical of the genus. A LIST OF SHELLS FROM THE EAST COAST OF FLORIDA. BY BRYANT WALKER.