MODIOLA. 103 



M. pedernalis, Romer,^ is a larger species with finer ribs, and the anterioi' part 

 of the shell nearly smooth. 



Distvlbiitioii. — Penia-hed of Redcliff. Crackers of Atherfield. Atherfield Beds 

 of East iShalford, Peasmarsh, Sevenoaks, and (ferruginous nodules) Littleton Pit, 

 near Guildford. 



MoDioLA (BitACHYDONTEs) STRiATO-cosTATA {d' Ovbignij), 1844. Plate XVII, figs. 9 a, h, 



10 a, b, 11 a — c. 



1844. Mttilus striato-costatus, A. d'Orhigny. Pal. Frauo. Terr. Cret , vol. iii, 



p. 281, p!. cccxlii, figs. 4 — 6. 

 1848. MoDioLA sTEi.\TO cosTATA, H. G. BroHH. Index Palseont., vol. i, p. 739. 

 1850. MiTTLUs sTRiATO-cosTATUs, A. d'Ovbigiiy. Proclr. de Pal., vol. ii, p. 166. 

 1867. MoDiOLA STRIATO-COSTATUS, F. J. Pictet and G. Gampiclie. Foss. Terr. 



Cret. Ste. Croix (Mater. Pal. Suisse, ser. 4), 



p. 510. 

 1871. — STRiATO-cosTATA, F. Stoliczku. Palseont. ludica, Cret. Fauna 



S. India, vol. iii, p. 373. 



Description.. — Shell small, oblong or ovate-oblong, short, inflated, somewhat 

 expanded, and also rounded and compressed posteriorly, ventral margin slightly 

 sinuous. Umbones not quite terminal. No carina; dorsal and ventral to a line 

 between the umbones and the posterior extremity the valves are sharply com- 

 pressed. Ornamentation consists of numerous fine radial ribs separated by narrow 

 grooves and covering the entire surface ; the ribs curve toward the dorsal margin. 

 The radial ribs are crossed at intervals by concentric ridges. 



Measurements : 



(1) 



(2) 



(3) 



(^) 



(5) 



9 



8 



8 



7 



5*5 mm 



(] 



5 



4-5 



4-25 



•3-5 „ 





4 



4-75 



b 



55 



Length . 

 Height . 

 Thickness . . 



(1) to (5) from Blackdown. 



Affiiiities. — The relation of this species to M. rectiensis is given above. It 

 seems to approach closely the form described by Pictet and Campiche ^ as Litho- 

 donius presteusls. 



Distribution. — BlackdoAvn Greensand. 



1 ' Die Kreidebild. von Texas ' (1852), p. 53, pi. vii, fig. 11. 



2 " Foss. Terr. Cret. Ste. Croix " (' Mater. Pal. Suisse,' ser. 4, 1867), p. 522, pi. cxxxvi, figs. 2—4. 



