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SUPPLEMENT TO THE BRITISH 



50. Thecidium Bouchardii, Dav. Dav., Ool. Mon., p. 14, PI. I, figs. 15 — 16; Sup., 



PI. XIII, figs. 1, 2, 3. 



Thecidea Botjchardi, E. Desl. Mem. Soc. Linn, de Normandie, vol. ix, pi. xii, 



figs. 15—19, 1853. 



Thecideum Bouc hardii, C. Moore. Proceedings of the Somersetshire Archaeological 



and Natural History Society, vol. for 1854, 

 p. 116, pi. i, figs. 11—13. 

 — — Quenstedt. Petrefactenk unde Deutschlands, Atlas, pi. lxi, figs. 



164—166, 1871. 



When I described this shell in 1851, the interior had not been discovered, since then 

 it has been well described and figured by Mr. C. Moore in the following words : — " The 

 interior of the ventral valve shows a slight middle septum, on each side of which are two 

 large scars, due to the attachment of the cardinal muscle, on the outer edge of which are 

 two small depressions, which received the adductor muscles : interior rugosely striated ; 

 the cavity of the valve in adult shells surrounded by a broad margin, having a wavy 

 appearance due to lines of growth. Interior of dorsal valve has a broad granulated 

 margin, within which is a very high central septum, nearly reaching the surface of the 

 opposite valve, from whence proceeds a granulated ridge, united by a bridge over the 

 visceral cavity : within this ridge is a smooth slightly concave space, between which and 

 the granulated interior is a small granulated ridge." 



This species occurs in the Middle and Upper Lias, and passes into the Inferior Oolite. 

 It was found by Mr. Moore in the last-named formation at Dundry. Mr. E. Deslong- 

 champs obtained the shell in the Upper Lias of May and Pontaine-Etoupe-four, near Caen, 

 in Normandy. 



51. Thecidium Dickensoni, Moore. Dav., Ool. Mon., p. 14, PI. XIII, fig. 19. 

 Nothing new. Inferior Oolite. 



52. Thecidium triangulare, d'Orb. Dav., Ool. Mon., p. 14, PI. I, figs. 11, 12, and 



Sup., PL XII, figs. 25, 26. 



Thecideum triangulare, Moore. Proceedings of the Somersetshire Archaeological 



and Natural History Society, vol. for 1854, 

 p. 121, pi. iii, figs. 11, 12. 

 — E. Desl. Mem. Soc. Linn, de Normandie, vol. ix, pi. xiii, 



figs. 28, 29, 1853, and vol. .\, pi. v, fig. 3, 1855. 



