246 NOTES ON THE BRITISH JURASSIC RRACHIOPODA. 



The Waldheimia?, as we understand it, he divided into two 

 groups, the Epithyridas cinctas and the Epithyridae impressaB. 

 The latter group correspond with Douville's Aulacothyris, 

 i.e. J comprise A.carinata, resupinata, etc.; while the Epithyridae 

 cindse is a most comprehensive group, as it includes such 

 diverse shells as Eudesia cardium ; Zeilleria quadrijida and 

 corniita ; Zeilleria vicinalis, digona, ohovata, etc. ; Ornithella 

 indentata and hucculenta ; Microthyris lagenalis ; Gincta 

 jiumismalis ; Terebratula punctata, ovatissiina. etc. (17). 

 Quenstedt evidently used his terms in a collective and not 

 generic sense, as may be gathered from the fact that he 

 included in his Ginctse, Terehratula as well as Waldheimia. 



Excellent specimens of G. numismalis are to be found in 

 the Jamesoni-beds at Kadstock ; also of G. cor in the Buck- 

 landi-beds (?) of the same district. 



Plestothyris, Douville, 1879. 

 (Type : P. vernueilli, Desl. sp.) 

 Etym. — 7rX7](rios, near ; OvpU, a small opening. 



According to Douville the species of Plesiothyris are few 

 in number, and represent aberrant forms. Although the 

 apophysary system of the type species is but very imper- 

 fectly known, yet it is generally supposed to be long and 

 characteristic of the Waldheimias. The beak is small and 

 bears on each side a prominent ridge, bounding a well- 

 marked area. Dorsal valve doubly folded. Form elongate 

 (13, p. 275). 



Deslongchamps, with some doubt, made Plesiothyris a 

 section of Zittel's Antiptychina. 



Plesiothyris is extremely rare in our Jurassic rocks, the 

 only species I know being Plesiothyris reversa, and hrodiei, 

 from the Inferior Oolite of Louse Hill, Dorset. 



