TOUCASIA. 207 



modified by pressure. On the other hand the shell in G. proboscideum, from 

 Blackdown, is replaced by silica, so that both its ornamentation and original shape 

 are perfectly preserved. 



French examples were identified by d'Orbigny 1 with this species, for which he 

 proposed the name Oardium Moutonianum since the specific name (tuberculata) 

 under which Sowerby originally described the species had already been used. 

 Sowerby, however, in the index at the end of vol. vi of the ' Mineral Conchology,' 

 had already substituted Gentianum for the name which he originally used. I have 

 not seen any specimen of G. Moutonianum, and am unable to say whether or not it 

 is really identical with G. Gentianum, but in d'Orbigny's figures the difference in 

 the sizes of the ribs and tubercles is seen on the anterior and posterior parts of 

 the shell only. 



G. Garolinum, d'Orbigny, 3 and G. inmquicostatum, Matheron, 3 are closely related 

 to, and perhaps identical with, G. proboscidetim. 



Types. — G. proboscideum, from the Upper Greensand of Blackdown, and 

 Gardita tuberculata (Cardium Gentianum), from the Upper Greensand of Devizes, 

 are in the British Museum. 



Distribution. — Upper Greensand (zone of Schbvnhachia rostrata) of Blackdown, 

 Haldon , Devizes, and Veutnor. 



Family— DICEE ATID^E, Ball 



Genus — Toucasia, E. Munier-Chalmas, 1873. 



(' Journ. de Conchyl.,' ser. 3, vol. xxi, p. 74. Douville, ' Bull. Soc. geol. de France,' ser. 3, vol. xv, 



1887, p. 762.) 



Touoasia Lonsdalei (Sowerby), 1836. Plate XXXIII, figs. 4— G. 



1836. Diceras Lonsdalii, J. de C. Sovjerby. Trans. Geol. Soc, ser. 2, vol. iv, 



pp. 268, 338, pi. xiii, fig. 4. 

 1850. Caprotina Lonsdalii, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 109 



(partim) . 



1854. Diceras Lonsdalii, J. Morris. Cat. Brit. Foss., ed. 2, p. 201. 



1855. Requienia Lonsdalei, S. P. Woodward. Quart. Journ. Greol. Soc, 



vol. xi, p. 53, fig. 29. 

 1871. Lonsdalii, F. StoliczJca. Palaeont. Indica, Cret. Fauna 



S. India, vol. iii, p. 233. 



1 ' Pal. Franc. Terr. Oct.,' vol. iii (1844), p. 34, pi. ccxlviii ; and ' Prodr. de Pal.,' vol. ii (1850), 

 p. 162. 



2 Op. cit. (1844), p. 29, pi. ccxlv. 



3 ' Catal. Foss. des Bouches-du-Rhone ' (1842), p. 157, pi. xviii, figs. 3, 4. 



