9. S. extrema.
Larger, 1,05 by .49; costae, narrow, 29. Found in vicinity of well, W. at extreme south end of key. Map 1, 9. 150. all dead; about the age of last, some specimens showing reddish markings. Plate 3, Figs. 1 2. [sic actually, Pl. 2, figs. 10, 11]