LIMA. 31 



Remarks. — The chief character in which Lima farringdonensis differs from 

 L. parallela seems to be in the possession of well-marked ribs over the whole of 

 the anterior area. It also differs from the majority of examples of L. parallela in 

 that the ribs only decrease in size to a very small extent in passing from the 

 anterior to the posterior part of the shell; and further, the shell is less inequilateral 

 than is usual in L. parallela. 



I am inclined to regard Lima farringdonensis as not more than a variety of 

 L. parallela, but without better material it is impossible to express a confident 

 opinion. Almost all the specimens seen are in the condition of internal casts in a 

 brownish ferruginous sandstone. 



Type. — The figure given by Sharpe is taken from a gutta-percha cast of an 

 external mould. It was obtained from Seende and is preserved in the Museum of 

 the Geological Society. 



Distribution. — Lower Greensand of Seende and Faringdon. 



Lima (Mantellum) uaultina, nom. nov. Plate V, figs. 16 — 20. 



? 1827. Plagiostoma elongata, J. de C. Sowerby. Min. Couch., vol. vi, p. 113, 



pi. dlix, fig. 2 (upper figure only). 

 1847. Lima parallela, A. d'Orbigny. Pal. Franc. Terr. Oct., vol. iii, p. 539, 



pi. ccccxvi, figs. 11 — 14. 

 1850. — d'Orbigny. Prodr. de Pal., vol. ii, p. 138. 



1855. G. Cotteau. Moll. Foss. de l'Yonne, p. 101. 



1854. elongata, J". Morris. Cat. Brit. Foss., ed. 2, p. 171 (partim). 



1875. A. J. Juices-Browne. Quart. Journ. Greol. Soc, vol. xxxi, 



p. 296. 

 1897. parallela, B. B. Neivton. Proc. Dorset Nat. Hist, and Antiq. Field 



Club, vol. xvii, p. 88, pi. iii, fig. 11. 

 1900. — — E. T. Newton and A. J. Juices-Browne. Cret. Eocks of 



Britain, vol. i, p. 449. 



Non 1850. Plagiostoma parallelus, J. de C. Sowerby in F. Dixon. G-eol. Sussex, 



p. 356 (p. 386, ed. 2), pi. xxviii, 

 fig. 16 (=L. elongata, Sowerby). 



Description. — Shell rather compressed, sub-quadrangular or nearly oblong, very 

 oblique, much longer than high, rounded posteriorly ; antero-dorsal margin long 

 and nearly straight, almost parallel with the postero- ventral margin. Apical angle 

 about 100°. Umbones pointed, close together. Ears of moderate size, the anterior 

 larger than the posterior. Anterior area large, slightly concave dorsally, orna- 

 mented with fine radial ribs. 



Ornamentation consists of 18 to 20 main ribs with a few smaller ribs pos- 

 teriorly. The ribs are strong, with sharp summits, but become somewhat 



