The aperture is small, oblique, with armature of two or three parietal lamellae and several deeply placed basal folds, all growing continuously from an early neanic stage.

[5] The shell, aside from its helicoid shape (not a character of great importance), differs from all Pupillidae in the arrangement of the lamellae and baso-palatal folds.

[5] By the accelerated lamellae and folds of the shell, which appear early in the neanic stage, Strobilops resembles various Tornatellininae (within Achatinellidae).

Radula with tricuspid central tooth with square basal plate, as large as the bicuspid laterals, the marginals multicuspid.

[5] By the structure of the male organs Strobilops resembles Vallonia, Pupilla, Lauria, the Achatinellidae, and some other groups are similar in having a bifurcate penial retractor and a long, tripartite appendix.

[5] Strobilopsidae appeared in the Upper Eocene of western Europe in several species having all the external characters of the genus Strobilops, and though the internal structure has not been worked out (in 1927),[5] it is safe to assume that they are closely related to the well-known Oligocene forms following them.