[1] Finlay's original text (the type description) reads as follows: Argalista nana n. sp.

Perhaps the best distinguishing character is the umbilicus, which in nana, is much smaller and almost filled up, appearing much as in Uberella vitrea (Hutton).

I have one typical specimen of fluctuata from 38 fathoms [69 m], Cuvier Island, otherwise all my shells of this species are from southern localities.

Nana may be the northern representative of fluctuata, but the occurrence of both forms together off Cuvier Island seems to negative this.

Nana is somewhat the size of Cirsonella densilirata Suter (a species very easily confused with the young of Argalista), but is much more tightly coiled, and has the typical Argalista pad, etc..This article incorporates public domain text coming from New Zealand from reference.