Abstract
This study is based on about 40 spp., almost all mollusks. Each sp. has a threshold limit for skeletal deposition, and this determines the temperature (temp.) at which shell will be formed. The determined average may vary a few degrees from the temp. of the locality and thus no one sp. can be used to determine average paleotemps. Fossils from interglacial Pleistocene deposits indicate a temp. within 1-2[degree]C of the present conditions.