. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. 182 GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA account is given of the occurrence and structure of the "concave deltidium" of Conch'tdtum. This plate in most specimens is truly concave and bears a median groove giving it the appearance of having been formed by the symphysis of two plates. One specimen of C. biloculare, however, shows toward the end of the beak that the plate is elevated above the margins of the delthyrium, forming a cover with nearly rectang
. Brachiopod genera of the suborders Orthoidea and Pentameroidea. Orthoidea; Pentameroidea; Paleontology -- Paleozoic. 182 GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA account is given of the occurrence and structure of the "concave deltidium" of Conch'tdtum. This plate in most specimens is truly concave and bears a median groove giving it the appearance of having been formed by the symphysis of two plates. One specimen of C. biloculare, however, shows toward the end of the beak that the plate is elevated above the margins of the delthyrium, forming a cover with nearly rectangular sides. In another specimen of the same species the plate is elevated fully 3 mm. dorsally from the del- specimens is more than half the length of the ventral shell and in some it extends for nearly the full length. The cardinalia, are, as is usual in the Pentameridae, the most interesting and significant structures of the genus. Here, as in Gyfidula, Pentamerella, etc., three distinct "plates" can be determined. The inner crural plates are convex and unite with a narrow flat shelf forming the inner postero-lateral margins of the valve. The union is marked by a low ridge and groove which forms the suture line between the valve and plate. ^ CD ci) (2) ^^. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Schuchert, Charles, 1858-1942; Cooper, G. Arthur (Gustav Arthur), 1902-. New Haven, Conn. [Tuttle, Morehouse & Taylor Co. ]
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