The Carboniferous System in Scotland Characterized by its Brachiopoda

This family, which has been termed Orthidœ by some authors, comprises several genera and subgenera, of which Strophomena, Streptorhynchus, and Orthis alone have been found represented in Scottish Carboniferous strata. The genus Orthis forms a well characterized group, especially specifically numerous and abundant in the Silurian and Devonian systems, is considerably reduced during the Carboniferous period to appear no longer (P) in subsequent stages. Two species alone have been hitherto discovered in the Carboniferous rocks of Scotland.