Polygyridae have gone through evolution primarily in the temperate zone of Earth and Millerelix is one of the only genera living in the tropics (Pilsbry 1940).  Polygyridae seem to be separated in regards to evolution depending on if a species lives in the east or west; species living in the east have evolved by demonstrating no need for a flagellum and therefore flagella are rarely present in Polygyridae in the east (Pilsbury 1940).

According to Pilsbury (1940), the genus Millerelix has gone through several evolutions of its own including development of a penis without sheath, an oviparous, a simple penis, and a biramose parietal tooth or a raised edge of the parietal callus on the shell, as well as, the loss of an epiphallus and flagellum (Pilsbry 1940).

The species Millerellix troostiana can be identified further by having a salient angle on the ramus of the parietal tooth, smaller basal tooth smaller than the outer tooth, and a ridged periphery or surface (Pilsbry 1940). 

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