GENERA OF SOME JURASSIC BRACHIOPODA 

 By S. S. Buckman, F.G.S. 



The genera are founded in the main on a study of internal details as 

 revealed by burning, though relative external development has also been 

 taken into consideration. 



Genotypes are written with sp. to denote that the species to be subse- 

 quently figured in a larger work will be the actual types, in case of questions 

 of misidentification. 



Family, Rhynchonellim; 



These Rhynchonellidae are divisible into three main series — Lceves, 

 Capillatce, Ornatce. Lceves are smooth and develop ribs directly on a smooth 

 stage ; CapillatcB have hair-like lines (striae) and then may develop ribs ; and 

 Ornatce have additional ornament like imbrication, or spines. 



The type of Rhynchonella, R. loxia, Fischer, is one of the Capillatce. The 

 acuta group which so much resembles it belongs to the Lceves, and so must 

 be removed. The result is that Rhynchonella which once covered hundreds 

 of species from the Ordovician to Recent, must now be confined, so far as 

 present knowledge goes, to one species, R. loxia. Cretaceous developments 

 may be looked for ; but many Cretaceous species belong to Cyclothyris, M'Coy, 

 distinguished by obsolete or obsolescent dorsal septum and broad dorsal 

 muscle-scars. 



Genera 



Pisirhynchia 

 Holcorhynchia 

 Gnathorhynchia 

 Calcirhynchia 



Sphenorhynchia 



Kallirhynchia 



Trop iorhynchia 



Piarorhynchia 



Cuneirhynchia 



Curtirhynchia 



Homceorhynchia 



Rhynchonelloidea 



Costirhynchia 



Grandirhynchia 

 Tetrarhynchia 

 Quadratirhynchia 

 Gibbirhynchia 



Rudirhynchia 



Stolmorhynchia 

 Plyctorhynchia 



Globirhynchia 

 Rh actor hynchia 



Genotypes 



LMVES 

 R. pisoides, Zittel 

 R. slandishensis , S. Buckm. 

 G. liostraca, S. Buckm. sp. 

 C. calcaria, nov. 



S. plicatella, Sow. sp. 

 K. yaxleyensis, Dav. sp. 

 T. thalia, d'Orb. sp. 

 P. radstockensis, Dav. sp. 

 C. dalmasi, Dum. sp. 

 C. oolitica, Dav. sp. 

 H. acuta, Sow. sp. 

 R. ruthenensis, Reynes sp. 

 C. costigera, nov. 



G. grandis, nov. 

 T. tetraedra, Sow. sp. 

 Q. quadrata, nov. 

 G. gibbosa, nov. 



R. rudis, nov. 



S. stolidota, nov. 



P. pentaptycta, S. Buckm. sp. 



LMVES ? 

 G. subobsoleta, Dav. sp. 

 R. rhacta, nov. 



Remarks 



R. calcicosta ; Dav. 

 series 



R. subringens, Dav. 

 series 



R. amalthei ; Dav. 



series 

 T. calcicosta, Quen. 

 series 



R. subtetrahedra, 

 Dav. series 





