322 



MOLLUSCOIDEA BRACHIOPODA 



SUB-KINGDOM V 



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

 tions. Silurian ; distribution probably general. 



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

 vexity of the valves reversed. North America. 



Clorinda, Barrande (Barrandella, Hall and Clarke). Small galeatiform 



FIG. 540. 



Conchidium bilociilare, Linn. Silurian ; Gottland. A, Shell of the natural size. B, Beak showing concave 

 deltidium. C, D, Interior of dorsal and ventral valves, respectively (x, Spondylium ; S, Median septum of 

 ventral valve, Fig. D; l>, Dental lamellae ; c, Crura ; S, Septum-like supports, Fig. C). 



Pentameroids 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. 



Gypidula, Hall (Sieberella, Oehlert), (Fig. 541). Galeatiform Pentameroids, 

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



FIG. 541. 



A-C, Gypidula galeata, Dalm. sp. Devonian ; Gerolstein, Eifel. A, Dorsal aspect, Vi- -B, Anterior aspect. 

 C, Transverse section below the hinge-line. (Lettering the same as in Fig. 540 C, D.) D Conchidium Knightii, 

 Sow. Silurian ; England. 1/2- 



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. 



Amphigenia, Hall (Enantiosphen, Whidborne). Elongate - ovate, high- 

 shouldered shells without median fold or sinus. Surface with concentric 

 growth varices and faint radial striae. Dorsal valve with a large sub-quadrate 

 hinge -plate perforated by the visceral foramen and without a cruralium. 

 Middle Devonian ; North and South America, France, and Germany. 



Camarophoria, King (Fig. 542). Shells Ehynchonelliform with the surface 



