Eucosmia Carpenter, 1864, non Stephens, 1831 (replacement name) Eulithidium is a genus of small colorful sea snails, marine gastropod mollusks in the family Phasianellidae, the pheasant shells.

However, the name Eucosmia was pre-occupied in zoology for a group of moths established by Stephens in 1829.

The molluscan Eucosmia was therefore called Eulithidium to distinguish it from the group of Lepidoptera.

[2] Species within the genus Eulithidium include:

This Phasianellidae-related article is a stub.