CLASS II BRACHIOPODA , 399 



and 593). Multiplicate Bhynchonellae with the pedicle opening below the 



Fi(!. 592. 



A, Rhynrhonella loxia Fiscli. Upper Jura ; Moscow. «, /), Profile 

 and dorsal view, Vi '> o> Internal mould ; d, Anterior view. B, 

 Cyclothyris quadriplicata (Quenst.). .Middle Jura; Boptingen, Wiir- 

 temberg. 



Fig. 593. 



A, Cyclothyris vespertilio 

 (Brocchi). Upper Cretaceous ; 

 Villedieu, Touraine. Vl- B, C. 

 lacunosa (Schloth.). Upper Jura ; 

 Engelhardsberg, Franconia. In- 

 terior of dorsal valve. 



venti-al beak. Embraces the bulk of Mesozoic Rhynchonellids. Genotype 

 Terebratula latissima Sdwerby. Distribution general in Mesozoic time. 



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

 Rhynchonella, most of which are found in Mesozoic strata and are now to be referred to the 

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

 loxia Fischer (Fig. 592) from tlie U]>per Jura of Russia. It is probable that there are no 

 Rhynchonellas in the Paleozoic. Hall and Clarke 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 triangular, usually smooth-shelled Ehi/nchonellae 

 without prominent fold and sinus. Alpine Trias. 



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

 sinus. Alpine Trias. 



Ehynchonellina 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 CEhlert. Large, strongly plicate 

 Bhynchonellae without fold or sinus. Cardinal 

 area well developed. Cretaceous ; Europe. 



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

 faintly plicate Bhynchonellae with a high ventral 

 beak and open delthyrium. No dental plates. F'«- ^^'^■ 



-P, IlemUhyris psittacea (Chem.). Recent: 



Kecent. Mediterranean. Vi- 



