Continuing my search through the screened remains of the Centerfield member of the Ludlowville formation (Devonian, Givetian stage), I came across a couple of specimens of Octonaria. This is a typical specimen that I took a photo of with my rigged up Canon S3 IS camera.
Looking through the book "Ostracods of the Middle Devonian Silica Formation" there are a couple of different Octonaria species. I think this most closely resembles Octonaria quadricosta based on plate 87 (pg. 358). It could be O. crescentiformis but I don't think that the furrows in the surface of the shell are curved enough.
References: "Ostracods of the Middle Devonian Silica Formation" by Kesling, R. V.; Chilman, R. B, 1978, FUMMP Papers on Paleontology No. 18