MODIOLA. 101 



1850. MiTYLUS UNDULATDS, A. d'Orhigtiy. Prodr. de Pal., vol. ii, p. 119. 

 1854. Cypricaedia undulata, J. Morrh. Cat, Brit. Foss., ed. 2, p. 199. 

 18G7. Mytilus (Modiola) undulatus, F. J. Pictet and G. Campk-hc Foss. 



Terr. Crct. Ste. Croi.x (Matrr. Pal. 



Suisse, ser. 4), p. 508. 

 1871. Modiola undulata, F. Sfolirzln. PalfEont. Indica, Cret. Faima S. India, 



vol. iii, p. 372. 



De>--crlpf!on. — Shell moderately elongate, compressed, enlarged posteriorly. 

 Dorsal margin nearly straight ; ventral oliliqne ; anterior ronnded. Umbones not 

 terminal, Avith a sharply marked cnrving carina extending to the postero-ventral 

 extremity. From the dorsal margin broad ribs start and are directed posteriorly, 

 afterwards curving to join the carina, where they end. Ventral to the carina the 

 shell is marked by fine lines only. 



Measurements : 



Length . . . . . . . . . So mm. 



Height (at the posterior end) . . . . . 18 „ 



Affinities. — This is distinguished from M. fin gel lifer a, Forbes, and M. Gilllcroni 

 (Pictet and Campiche) by the shorter shell, the carina, the small curvature of the 

 ribs, and the absence of bifurcation in them. 



The generic position of this species cannot be stated with certainty, since the 

 type specimen is the only example seen and the interior is unknoAvn. 



Ti/pe. — In the Museum of the Geological Society of London (No. 2088). 



Distrlhvtion. — Atherfield Clay of Atherfield. 



Sub-genu!^ — B ijachydontes, Swainson, 1840. 

 (• Treatise on Malacology,' p. 384.) 



Modiola (Brachydontes) G-ueeangeei ? {tVOrhvjny), 1844. Plate XVII, figs. 4, 



1844. Mytilus GtUERAngeei, A. d'Orhlgny. Pal. Franc. Terr. Cret., vol. iii, p. 



282, pi. cccxlii, figs. 7 — 9. 

 1850. Mitylus — d'Orhigny. Prodr. de Pal., vol. ii, p. 166. 



1862. Brachydontes Guerangeri, /. G. Chenu. Manuel de Concliyl., vol. ii, 



p. 154, fig. 762. 

 1867. Mytilus Guerangeri, F. J. Pictet and G. Campiche. Foss. Terr. Cret. 



Ste. Cioix (Mater. Pal. Suisse, ser. 4), p. 509. 

 1867. — — E. Gueranger. Album Paleont. de la Sarthe, p. 17, 



pi. xxiii, fig. 3. 

 1871. Modiola Guerangeri, i^ StoHczka. Palseont. Indica, Cret. Fauna S. India, 



vol. iii, p. 373 {Brachydontes). 



