]22 
BRACHIOPODA. 
12. Thecidium Dickinsonii. 
Shell minute, transversely oval, smooth ; dorsal valve convex ; 
ventral valve attached by its whole surface ; area nearly as wide 
as the shell, straight. Lon. 1^, lat. 2^ hnes. 
Thecidea Dickinsonii, [Moore) Davidson, Mon. 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<i 
14. Thecidium triangulare. 
Shell triangular, slightly bilobed, smooth, gibbose ; hinge-area 
triangular, high and narrow ; deltidium distinct. Lon. 1, lat. 1 
line. 
Thecidea triangularis, Davidson, 1851, 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. 316? not described. 
Thecidea Virdunensis, Buvignier, 1852, Geol. de la Meuse, p. 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 prominent muscular fulcrum ; internal margin 
thickened and granulated ; apophysary ridge simple, parallel 
with the margin, and a little within it, deeply bilobed. Lon. 1, 
lat. 1 line. 
Thecidea rustica, [Moore) Davidson, 1851, p. 15. pi. 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 lines. 
Tliecidea Bouchardii, Dav. Mon. Ool. 1851, p. 14. pi. 1. f. 15, 
16; Ann. Nat. Hist. April 1852, pi. 14. f. 10-12. 
Fossil. Lias [Marlstone). Ilminster, attached to i?/)y«cAone/Zffi; 
France. 
