CLASS TI 



BEACHIOPODA 



403 



Girtyella Weller. Like Dielasma, but the cruralium is supported by a 

 septum. Lower Carboniferous ; North America. 



Bielasmoides Weller. Like Girtyella, but with septal plates instead of 

 crural lamellae. Lower Carboniferous ; North America. 



Cranaena Hall and Clarke. Dental lamellae strong. Socket plates 

 uniting into a hinge -plate which is posteriorly perforate ; no cruralium. 

 Devonian and Lower Carboniferous. Subgenera : Hamburgia and Bielasmella 

 Weller. Lower Carboniferous, North America. 



Dielasmina Waagen. Plicated Dielasmids, Carboniferous ; India. 



Beecheria Hall and Clarke. Like Dielasma, but without dental lamellae ; 

 cruralium completely sessile. Carboniferous ; North America and India. 



Bowleyella AVeller. Both valves with median septa. Lower Carboniferous ; 

 North America. 



Heterelasma Girty. Smooth Dielasmids with a ventral fold and a dorsal 

 sinus. Median septa in both valves. Hinge-plate rudimentary. Permian ; 

 Texas. 



Hemiptychina Waagen. Plicated Dielasmids without dental plates. Carboni- 

 ferous to Permian ; India. 



Notothyris Waagen (Bostranteris Gemmellaro). Coarsely plicate biconvex 

 shells with a perforate hinge-plate as in Centronella. Permian ; India. 



Subfamily C. Terebratdlinae Dall. 



Post-Paleozoic Terehratulidae tvith a short loop. A median unpaired coiled arm 

 exists in Eecent genera. Triassic to Recent. 



Terebratula Miiller 1^76 (as redefined by Buckman 1907) (Fig. 599). 

 Genotype Anomia terehra- 

 tida Linn. Pliocene. Large 

 biplicate shells of the Ter- 

 tiary of Europe. 



Musculus Quenstedt. 

 Buckman states that this 

 term will be useful for the 

 Cretaceous biplicate species. 

 Genotype Terebratula acuta 

 Quenst. Europe. 



Epithyris Phillips, non ^'\^^^^ ^^^^^^^^Sd^ 



King. Buckman uses this 



Pig. 599. 



Fig. 6UU. 



Pygope diph y a (Colonna,). Titlionian ; 

 Trent, Tyrol. Vi- 



genus for a small group 



of Jurassic biplicate forms. m^IZ' Mi^l^ j^IrafS 



Genotype Terebratula maxil- "ear Aarau, Switzerland, i/i- 



lata Sowerby. Europe. 



Ehaetina and Ziigmeyeria Waagen. These genera comprise biplicate 

 forms, Trias ; Europe. 



Pygope Link {Diphyites Schroter) (Fig. 600) ; Antinomia Catullo ; and 

 Pygites de Haan (as redefined by Buckman 1906). Three independent genera, 

 according to Buckman, with the shells originally bilobed, the two lobes often 

 uniting anteriorly in adult specimens, but leaving posteriorly a median 

 hollow space passing through both valves. Developed out of a Glossothyrid- 

 like form. Jurassic ; Europe. 



