106 PERMIAN FOSSILS. 



The genus Schizophoria} I propose to typify with the Conch. Anom. resupinatus of 

 Martin, and to provisionally characterise it as having an open fissure, often rounded 

 umbones, large punctures,^ and the valves in general arcuately striated in the cardino- 

 lateral regions. The genus thus characterised and typified readily resolves itself 

 into a receptacle for most of the shells which M. de Verneuil ■ has included in his 

 groups Sinuata, Arcuato-striatcB, and Plicosa? 



Since the period referred to, Mr. T. Davidson, besides rendering much valuable 

 aid as regards the genera just discussed, has thrown considerable light on certain 

 shells, the afiinity of which were previously involved in the greatest obscurity. It is 

 now clear, from the figures and descriptions published by this learned brachiopodist, 

 that the Anomia hiloha of Linnaeus, and the TerebratuUtes biforatus of Schlotheim, are 

 not Spirifers as they have generally been considered, but species typical of new genera 

 allied to the last-described genus, and belonging to the same family, — StrophomenideB. 

 Impressed with this view, I here take the opportunity of instituting for these shells the 

 following two genera. 



Platystropliia^ King. — Type TerebratuUtes biforatus, Schlotheim. 



Diagnosis. — A Strophomenidia ; widest in the transverse direction ; tumid ; sub- 

 aequivalve ; plicated or striated ; with large punctures, and a wide bi-areagerous 

 hinge. Umbones prominent, strongly incurved, and approximating. Areas with an 

 open fissure. Large valve deeply sinuated medio-longitudinally. 



Besides the typical species, this genus embraces Platystrophia Tcheffkini [Spirifer id.), 

 De Vern., P. dentata {Porambonites id.), Pander, P. costata {Porambonites id), Pander, 

 and P. terebratuliformis {Spirifer id.), 'M.' Coy, all of which belong to the Silurian period. 



Dicalosia," King. — ^Type, Anomia biloba, Linnaeus. 



Diagnosis. — A Strophomenidia ; deeply constricted medio-longitudinally ; striated ; 

 widest at its anterior half; inaequivalved ; and furnished with a narrow bi-areagerous 

 hinge. Umbones slightly gibbous. Area of the large valve with an open fissure. 



The published species of this genus are few in number, and appear to belong 



^ From ffx'Sw, I split, and cpopeuj, I carry. 



2 The species typical of the genus has a punctated structure. M. de Verneud's Schizophoria punctata 

 (Orthis id.) possesses this character (vide Bull. Geol. Soc. de France, 2"= serie, t. t, p. 35, pi. iv, fig. 8) ; 

 and Mr. Morris has noticed it in Schizophoria elegantula {Orthis id), Dalman (vide Geol. Journal, vol. ii, 



p. 389). 



3 It is extremely probable that some of the shells included in these groups belong to uncharacterised 



genera. 



-' From TrXarvs, wide, and irrpo^ew, to turn (as a hinge). 



= From bis, twice, and koiXos, a cavity; in allusion to the shell appearing as if separated into two cavities. 



