Crassatina nummaria is a species of bivalve, a marine mollusc in the family Crassatellidae. Fossils of the species date to the Nukumaruan stage (2.40 million years ago) of the Pleistocene in New Zealand.
In the original description, Powell described the species as follows:
The holotype of the species has a height of , a length of , and a thickness of for a both valves together.
The species was first described by A. W. B. Powell in 1931, using the name Talabrica nummaria. While the accepted name in New Zealand as of 2009 was Talabrica nummaria, the World Register of Marine Species lists the accepted name as Crassatina nummaria. The holotype was collected in January 1931 by Powell from Nukumaru Beach near Waiinu Beach in South Taranaki, and is held in the collections of Auckland War Memorial Museum.
Fossils of the species are found in association with Barytellina crassidens and Anomia trigonopsis.
This extinct marine species occurs in the Pleistocene Nukumaruan stage (2.40 million years ago) in New Zealand, including the Nukumaru Brown Sand. Fossils of the species have been found along the South Taranaki-northwestern Whanganui District coast, and near Pahiatua in Manawatà «âÂÂWhanganui.