Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 80. (Budapest 1988)

Pálfy, J.: Middle Triassic rhynchonellids from the Balaton Highland (Transdanubian Central Range, Hungary)

The beak is pronounced, erect. The pedicle opening is hypothyridid, the deltidial plates are well developed. Internal characters (Fig. 13): The sectioned specimen was too silicified to distinguish clearly all the fine details of the internal structure. However, some valuable observation could be made. Pedicle valve: The delthyrial cavity is rounded, almost circular. The umbonal cavities were filled with silica, but the placement of the subparallel dental plates can be assumed. The hinge teeth are simple, no denticula were distinguished. Brachial valve: The hinge plates are narrow, almost horizontal. The septalium is shallow, supported by a moderate dorsal median septum. The sockets are deep, bordered by marked inner and outer socket ridges. The crural bases are located in the middle of the hinge plates. The crura are of calcarifer type. Fig. 13. Piarorhynchella trinodosi (BITTNER, 1890): a series of 13 transverse sections through the posterior part of a specimen from Felsőörs. Original length 7.6 mm. The crura persisted to 2.6 mm from the posterior end of the shell. The internal part of the shell was partly silicified.