Notes on the Fauna of the Chipola Formation - XIX on the Presences of Gastrochaena (Spengleria) (Mollusca: Bivalvia)

Abstract

The Gastrochaenid subgenus Spengleria Tryon, 1862, is known, according to the Treatise on Invertebrate Paleontology (1969, p. N699), only from the Recent faunas of the East and the West Indies. It was, therefore, unexpected to find it represented in the collections by a single valve from each of three localities in the Chipola Formation of Calhoun County, Florida. Subsequently, during the preparation of the present paper, it was noted that a Paleocene species described by G. D. Harris as Gastrochaena cimitariopsis from the "uppermost layers of the Midway limestone as exposed on the Chattahootchee river at Fort Gaines... Georgia" (1896, p. 70 [ 184], pl. 6 [ 16], fig. 13) had been questionably referred to Spengleria by Dall (1898, p. 824). Examination of Harris' original illustration appears to confirm Dall's conclusion. Harris gave no dimensions for his specimen other than to state that the figure was "twice natural size";  measurement would suggest a specimen about 7.5 mm long and 4.0 mm high. Accordingly it seems probable that Spengleria may range throughout the Tertiary of eastern North America.