122 brachiopoda. 



12. Thecidium Dickinsonii. 



Shell mmute, transversely oval, smooth ; dorsal valve convex ; 

 ventral valve attached by its whole surface ; area neai'ly as wide 

 as the shell, straight. Lon. H, lat. 2i lines. 



Thecidea Dickinsonii, {Moore) Davidson, Mori. Ool. p. 14. 



Fossil. Inferior Oolite. Somersetshire, attached to Terebratulce . 



13. ? Thecidium dubium. 



Thecidea dubia, D'Orb. Prod. i. p. 288 (undescr.). 

 Fossil. Inferior Oolite. France. 



14. Thecidium triangulare. 



Shell triangular, slightly bilobed, smooth, gibbose ; hinge-area 

 triangular, high and narrow; deltidium distinct. Lon. 1, lat. 1 

 Ime. 



Thecidea triangularis, Davidson, i.S5l, Mon. Ool. p. 14. pi. 1. 

 f. 11, 12; Ann. Nat. Hist. April 1852, pi. 14. f. 13. 

 D'Orb. MS. 1849, Prod. i. p. 31 (i? not described. 

 Thecidea Virdunensis, Buvignier, 1852, G^ol. de la Meuse,j). 27. 



pi. 20. f. 33-35. 

 Thecidea Davidsoni, Buv. id. p. 26. pi. 20. f. 36-38. 

 Fossil. Lias (Marlstone). Somerset (Moore). 

 Inferior Oolite. Cheltenham (Wright). 

 Bath Oolite. Caen (D'Orb.) ? 



15. Thecidium rusticum. 



Shell minute, squarish, slightly convex, smooth ; interior of 

 dorsal valve with a ])rominent muscular fulcrum ; internal margin 

 thickened and granulated ; apo})hysary ridge simple, jiarallel 

 with the margin, and a little within it, deeply bilobed. Lon. 1, 

 lat. 1 line. 



Thecidea rustica, (Moore) Davidson, 1851, p. 15. jjI. 1. f. 14. 

 Fossil. Upper Lias. Ilminster. 



16. Thecidium Bouchardii. 



Shell transversely elongated, smooth, attached by the whole 

 surface of the ventral valve ; hinge-area long and narrow ; del- 

 tidium broad, short and elevated ; dorsal valve convex ; margin 

 shelving. Lon. 3, lat. 4 hnes. 



Thecidea Bouchardii, Dav. Mon. Ool. 1851, p. 14. pi. 1. f. 15, 

 16; Ann. Nat. Hist. Aprd 1852, pi. 14. f. 10-12. 



Fossil. Lias (Marlstone). Ilminster, attached to Rhynchonellce ; 

 France. 



