We have restudied some of the material of a fossil anostracan originally di
scussed and illustrated by Palmer from the Middle Miocene, Barstow Formatio
n, near Yermo, California, and we now recognize it as a new species, Branch
inecta barstowensis. It is the best-preserved fossil anostracan known to da
te. The closest affinities of this species are with B. pollicifera Harding,
1940. collected from the mountains of Peru and Bolivia around Lake Titicac
a.