Emarginella flabellum Dall, 1896 superseded combination Zeidora flabellum is a species of sea snail, a marine gastropod mollusk in the family Fissurellidae, the keyhole limpets and slit limpets.

(Original description) The small shell is translucent white, depressed, wider in front, narrow behind, squarish at both ends.

The slit is short, one-fourth as long as the shell, widest in front, straight.

The sculpture consists of fine concentric incremental lines and very fine elevated threads, which start from the anal fasciole and curve outward toward the margin with very few intercalated threads.

[3] This marine species was found off Clarion Island, Lower California, Mexico.