NOTES ON THE BRITISH JURASSIC BRACHIOPODA. 235 



Also a described specimen of Ter. perovalis, Sow., from the 

 Inferior Oolite of Dinnington (23). 



The type of Ter. ether idgei, Da v., from the Inferior Oolite 

 of Dandrj, is located in our Museum, also of Ter. punctata, 

 var. radstockensis, Dav., from the Lias of Radstock (22). 

 The types of Ter. eudesi, Oppel, and tawneyi, Whid., were 

 found in the Inferior Oolite of Dandrj; Ter. eudesi is abun- 

 dant in the co7icavum-heds of that place, especially at the 

 western end of the hill. 



DICTYOTHYRIS, Douville, 1879. 

 Etym. — SiKTvov, a net; Ovpts, a small opening. 



The shells familiarly known to us as Terehratula hyhrida 

 and moTierei, from the Inferior Oolite of Dorset ; Ter. coarc- 

 tata, from the Great Oolite and Bradford-clay in the neigh- 

 bourhood of Bath ; Ter. coardata, var. reticulata, from the 

 Fuller's Earth, near Frome ; and Ter. hentleyi, from the 

 Cornbrash of Stilton, near Peterborough, are the Jurassic 

 forms which belong to Douville's Bictyothyris. With the 

 exception of Dicty. hentleyi, they may be recognised by the 

 beautiful reticulated appearance of the surface of the valves, 

 formed by the longitudinally raised striae intersected by 

 transverse lines. 



Bictyothyris is characterized by a mode of plication of its 

 valves, the opposite to what obtains in the '■^ Biplicatse'^ 

 {Terehratula) of Douville (13). Davidson, however, did not 

 consider this to be of sufficient importance to warrant 

 the separation of these shells from Terehratula, in which 

 genus he placed them. (Ehlert makes Bictyothyris a sub- 

 genus of Terehratula. 



With the exception of Bicty. coarctata, all the species of 

 Bictyothyris are rare, Bicty. hyhrida especially so. 



