CLASS II 



BRACHIOPODA 



395 



Stricklandinia Billings. Similar to Conchidium, but with a straight hinge- 

 line and no prominei*t arched ventral beak. Spondylium small and short, 

 supported by a short median septum. Silurian ; North America, England 

 and Gotland. 



Pentamerus Sowerby (PentasÜre Blainville). Like Conchidium, but with 

 smooth Shells, or sometimes with a few broad and obscure radiating undula- 

 tions. Silurian ; distribution probably general. 



Orthotropia Hall and Clarke. Similar to small Pentamerus, but with a 

 short hinge-line. Differs also internally. Silurian ; Wisconsin. 



Holorhynchus Kiär. Transverse Pentamerus, with incipient plications. 

 Spondylium not supported by septum. Silurian ; Norway. 



Cajpellinia Hall and Clarke. Like Pentamerus, but with the relative con- 

 vexity of the valves reversed. Silurian ; North America. 



Clorinda Barrande {Barrandella Hall and Clarke). Small Gijpidula-\ikQ 

 Pentamerids usually with smooth shells, rarely plicate. Spondylium with- 

 out a supporting septum. Silurian ; North America and Europe. 



Pentamerella Hall. Much like Clorinda, but with strong plications and a 

 narrow cardinal area. Devonian ; North America. 



Sieberella CEhlert ; and Gypidula Hall. (Fig. 588.) Galeatiform Penta- 



FiG. 588. 



Ä-Ct Gypidula galeata (Dalm.). Devonian ; Gerolstein, Eifel. A, Dorsal aspect, i/i. B, Anterior aspect. 

 C, Transverse section below the hinge-line. (Lettering the same as in Fig. 587, C, D.) D, Conchidium knightii 

 (Sow.). Silurian ; England. 1/2. 



merids,with the median sinus on the dorsal, and the fold on the ventral valve. 

 In Sieberella there is no cardinal area, but in typical Gypidula there is a well- 

 defined, cross-striated, cardinal area. 

 Surface smooth or plicate. Silurian and 

 Devonian; North America and Europe. 



Branconia Gagel. Like Gypidula, 

 but with sharp and few plications, as 

 in Pugnax of the Rhynchonellids. Sil- 

 urian ; Glacial drift of Germany. 



Seminula M'Coy {non auct.). Ac- 

 cording to Buckman the genotype is 

 Terebratida penta'edra Phillips. Shells 

 rhynchonelliform with the surface 

 more or less strongly plicated. Spon- ^,^-7 1 iV^iil^^t in^^^^^^^^^^ 



dvlium SUDÜOrted bv a long median of shell, enlarged. pr, Cardinal process ; c, Crtira ; 

 •^ , T^ • i. -n • T? .« ^, Spondylium; g, Dental plates of dorsal valve; 



septum. Devonian to Permian ; Europe, ,,; g'^ Median septa. 



India and North America. Subgenus 



Camarophoria King (Fig. 589) may, according to Buckman, be used for the 



more transverse, fully plicate shells. 



Fig. 589. 



