398 MOLLUSCOIDEA phylum v 



Rhynchotetra Weller, Elongate, coarsely plicate shells nearest to 

 Camarotoechia. Dental lamellae uniting into a spondylium, which is supported 

 by a median septum. Lower Carboniferous ; North America. 



Tetracamera Weller. Like Camarotoechia, but with rostral dorsal cavity 

 divided into four chambers by the crural plates and a median septum. A 

 spondylium present, but practically without septal support. Lower 

 Carboniferous ; North America. 



Paraphorhynchus Weller, Coarsely plicate Ehynchonellae with fine 

 additional striae. Interior much as in Camarotoechia. Lower Carboniferous ; 

 North America. 



Leiorhynchus Hall. Internally like Camarotoechia, but with the plications 

 on the lateral slopes usually faint or obsolete. Devonian to Carboniferous. 

 Subgenus : Moorefieldella Girty. Differs in having a finely plicate surface. 

 Lower Carboniferous ; North America. 



Wilsonia Kayser (Uncinulina Bayle). Sub-cuboidal or sub-pentahedral 

 Bhynchonellae with the low plications marked anteriorly by fine median lines. 

 Internally as in Camarotoechia. Silurian to Lower Carboniferous. North 

 America and Europe. 



Hemiplethorhynchus von Peetz. Very similar to Camarotoechia. Crural 

 cavity with a posterior triangular opening. Upper Carboniferous ; Altai, 

 Russia. 



Hypothyridina Buckman (Hypothyr^ King, non Hubner 1822). Sub- 

 cuboidal Bhynchonellae with a very rudimentary dorsal median septum. 

 Plications as in Wilsonia. Vascular sinus frequently strongly impressed in 

 the ventral valve. Devonian ; North America and Europe. 



Pugnax Hall and Clarke. Bhynchonellae with a deep dorsal and shallow 

 ventral valve, and very prominent fold and sinus. Dental lamellae short ; 

 no median septa. Devonian to Carboniferous ; North America and Europe. 

 Subgenus : Allorhynchus Weller. Has decided angular plications as in 

 Camarotoechia. Lower Carboniferous ; North America. 



Pugnoides Weller. Exterior like Pugnax, with the internal characters of 

 Camarotoechia. Lower Carboniferous ; North America. 



Shumardella Weller. Much like Pugnax, but with a short dorsal median 

 septum that is not connected with the hinge-plate. Lower Carboniferous ; 

 North America. 



Bhynchopora King (Bhynchoporina QEhlert). Plicate Bhynchonellae with 

 the shell substance punctate. A crural cavity as in Camarotoechia, but roofed 

 over by the hinge- plate. Dental lamellae well developed. Range from 

 Lower Carboniferous to Permian ; Europe and North America. 



(?) Torynifer Hall and Clarke. May be Bhynchonellae with the crural plates 

 united into a hinge-plate. Genus not yet defined. Lower Carboniferous ; 

 North America. 



Terebratuloidea Waagen. Bhynchonellae with very large apical truncate 

 foramen, but without dental plates or median septa. Carboniferous to 

 Permian ; India. 



Bhynchonella Fischer (as restricted by Hall and Clarke) (Fig. 592, A). 

 Sub-pyramidal pauciplicate shells with the pedicle opening as in Cyclothijris. 

 Dental lamellae and a dorsal median septum present. Jurassic and 

 Cretaceous. 



Cyclothyris M'Coy (as redefined by Buckman in 1906) (Figs. 592, B, 



