CLASS II BRACHIOPODA 399 



;ind 593). Multiplicate Bhynchonellae with the pedicle opening below the 



A, Rhynchonella loxia Fisch. Upper Jura ; Moscow. a, b, Profile 

 and dorsal view, i/j ; c, Internal mould ; d, Anterior view. B, 

 Cyclothyris quadriplicata (Quenst.). Middle Jura; Bopflngen, Wür- 

 temberg. 



Fig. 593. 



A, Cyclothyris vespertilio 

 (Brocchi). Upper Cretaceous ; 

 Villedieu, Touraine. Vi- -ß. C. 

 lacunosa (Schloth.). Upper Jura ; 

 Engelhardsberg, Franconia. In- 

 terior of dorsal valve. 



ventral beak. Embraces the bulk of Mesozoic Rhynchonellids. Genotype 

 Terebratula latissima Sowerby. Distribution general in Mesozoic time. 



Upwards of 700 species of Brachiopods have been described under the name of 

 Rhynchonella, niost of wliich are found in Mesozoic strata and are now to be referred to the 

 genus Cyclothyris. But few Rhynchonellids agree with the genotype, which is Rhynchonella 

 loxia Fischer (Fig. 592) from the Upper Jura of Russia. It is probable that there are no 

 Rhynchonellas in the Paleozoic. Hall and Ciarke and Weller have shown that most of the 

 American Paleozoic species belong to other genera. Bittner has also removed from 

 Rhynchonella many Triassic species. 



Halorella Bittner. Sharply plicated Bhynchonellae with a median sinus 

 on both valves. Alpine Trias. 



Austriella Bittner. Small triangulär, usually smooth-shelled Bhynchonellae 

 without prominent fold and sinus. Alpine Trias. 



Norella Bittner. Like Austriella, but with prominent anterior fold and 

 sinus. Alpine Trias. 



Bhymhonellina Gemmellaro. Transverse Bhynchonellae with fine radial 

 Striae. Cardinal margin nearly straight, with a low concave ventral area. 

 Crura very long, ventrally curved. Median septum of dorsal valve faint. 

 Jura ; Sicily and the Alps. 



Dimerella Zittel. Small plicate shells with a high umbo and a straight 

 hinge-line. Delthyrium large, with linear deltidial plates. Dorsal valve with 

 a high median septum extending to the ventral 

 valve. Alpine Trias. 



Peregrinella (Ehlert. Large, strongly plicate 

 Bhynchonellae without fold or sinus. Cardinal 

 area well developed. Cretaceous ; Europe. 



Hemithyris d'Orb. (Fig. 594). Smooth or 

 faintly plicate Bhynchonellae with a high ventral 

 beak and open delthyrium. No dental plates. . Fif=- 5^^. 



_-, j. ./ Jlemi thyris pstttacea (Chem.). Recent 



Kecent. Mediterranean. Vi. 



