244 NOTES ON THE BEITISH JURASSIC BRACHIOPODA. 



without projecting" part at the periphery ; fi'ont round, 

 square ended or sh'ghtly bilobed (12, p. 273). 



This section is represented in the Middle Lias of the 

 Ilminster district by 0. indentata, Sow. ; in the Fuller's 

 Earth of the Sherborne district by 0. cadomensis, E. Desl. ; in 

 the Cotteswolds by 0. hughesl, Walker ; in the Fuller's Earth 

 of the Bath district by 0. ornithocephala, Sow. ; and in the 

 Middle Oolites by 0. umbonella, Lam., and 0. buccidenta, 

 Dav. 



Deslongchamps made Ornithella, like Microthyris, Aula- 

 cothyj'is, and Cincta, sections of his genus Zeilleria. 



MiCEOTHYRia, Eug. Deslongchamps, 1884. 



(Type : M. lagenalis, Schl. sp.) 

 Etym.— /x-tKpos, small ; 6vpi<i, a small opening. 



In this section the beak is very much recurved in the form 

 of a crook, which is finely pointed, without lateral carinee, 

 and pierced with a foramen of small dimensions. The form 

 is elongated, swollen at the umbones, depressed and sharply 

 truncated at the front (12, p. 274). 



Deslongchamps said that Microthyris is one of the best 

 characterized groups of tbe Zeillerise ; and that it is com- 

 posed of only a single species, the Te7\ lag enalis (Schl.), which 

 is confined to the Cornbrash. 



Fine examples of this species, and a so-called variety 

 sub-lag enalis, Dav., are found in the Cornbrash of Gloucester- 

 shire and Oxfordshire. 



AuLACOTHYRis, Douville, 1879. 

 (Type : A. resupinata, Sow. sp.) 

 Etym. — avAa^, a furrow ; OvpL<;, a small opening. 

 The shells in this section can easily be distinguished from 



