48 rRETAC'EOUS LAMELLTBT^AXriTTA. 



Affinifie.^. — This species is easily distinguished from L. Tomhecliana (see p. 45) 

 by its rehitively higher and less inflated form, l)y the narrow ribs, and by the less 

 symmetrically placed ribbed area. 



In its narrow ribs L. Dtipiniana resembles L. svhcvrjji'ilatrrnlift, d'Orbigny (see 

 page 49) but the ribs in the latter arc distributed over the groatoi- ]iai-t of the 

 shell and are more widely separated and more numerous. 



The specimens referred to L. semimdcata by Forbes are poorly i)rescrved, Init 

 probably belong to this species. 



Types. — From the Neocomian of MaroUes (Aube) and Saint Sauveur (Yonne). 



Distribution. — Tealby Limestone (zone of li. hrvnsvicensis) of North Willing- 

 ham. Ferruginous Sands of Slinnklin. Athcrfiold Beds of "Rcdliill. TTytlio Beds 

 of Hythe (.//-/'• Topley). 



Lima (Limati la) Fittoni, <VOyhi,jmj, 1850. Plate VII, figs. 12—14, 15 a—c. 



183C. Lima, semisdlcata, J. de C. Sowerhy. Trans. Geol. Soc, ser. 2, vol. iv, 



pp. 336, 359 (not 129, 158), j.!. 

 xi, fig. 10. 

 1850. — Fittoni, A. (TOrhifjny. Prodr. de Pal., vol. ii, p. 82. 

 1854. — sEMi.suLCATA, /. Morris. Cat. Brit. Pos-s., cd. 2, p. 172 (^partim). 

 1869. — — J^. .7. PIrtrl and O. Cnnpichi'. Foss. Terr. Crut. Slo. 



Croix (Mater. Pal. Suisse, 

 ser. ■>), p. 166 {partim). 



Descrijdion. — Shell oval, moderately convex, higher than long, slightly in- 

 equilateral, with rounded margins, the posterior being more convex than tlie 

 anterior. Umbones small, close together. Ears equal. 



Ornamentation consists of from 13 to 15 radial ribs with sharp summits, 

 separated by narrow grooves. Pointed projections are present on the summits 

 of the ribs, especially near the ventral border of the shell. Tlie auterioi' and 

 posterior parts of the shell are without ribs. The riljbed area is nnsymmetri- 

 cally placed, and the anterior smooth jiart of tlie shell is considerably smaller 

 than the posterior part. Fine concentric ridges are seen on well-preserved 

 specimens. 



Measurements : 



(1) (2) (3) (4) (r,) 



Length .10 9 8 8 7 



Height . IG 14 14 13 12-5 

 (1, 3 — 7) Upper Greensand, Haldou. 



(2) „ „ Blackdown. 



