MERICA CONTORTA. 395 



1871. Cancellaria contorta, A. Bell, Ann. Mag. Nat. Hist. [4], vol. vii, p. 354. 



1872. Cancellaria contorta, S. V. Wood, Mon. Crag Moll., 1st Suppl., pt. i, p. 46, pi. vi, fig. 19. 

 1872. Cancellaria contorta, von Koenen, Mioc. Nord-Deutsch. Moll. Faun., pt. i, p. 25, no. 20. 

 1872. Cancellaria contorta, A. and R. Bell, Proc. Geol. Assoc, vol. ii, p. 203. 



1876. Cancellaria contorta, Seguenza, Boll. R. Com. Geol. Ital., vol. vii, p. 8, no. 439. 



1886. Cancellaria contorta, Dollfus et Dautzenberg, Feuilles des jeunes Nat., vol. xvi, p. 103. 



1890. Cancellaria contorta, C. Eeid, Plioc. Dep. Brit., p. 239. 



1890-1904. Cancellaria contorta, Sacco, Boll. Soc. Geol. Ital., vol. ix, p. 263, no. 3852, 1890 ; C. (Con- 



tortia) contorta and vars, Moll. Terr. Terz. Piem., pt. xvi, p. 49, pi. iii, figs. 24 — 26, 1894 ; C. (Merica) 



contorta, pt. xxx, p. 119, 1904. 

 1899. Merica contorta, Cossmanu, Ess. Palcoconch. conipar., vol. iii, p. 15. 



Specific Characters. — Shell ovato-elongate ; whorls convex, the last much the 

 largest, two-thirds the total length, acuminated at the base, reticulated by fine, 

 oblique longitudinal costse and by raised spiral ridges ; spire short, rapidly and 

 regularly diminishing in size towards the apex ; suture deep ; mouth rather large, 

 ovate; outer lip fluted within; columella contorted, with three folds. 



Dimensions. — L. 18 mm. B. 10 mm. 



Distribution. — Not known living. 



Fossil: Lenham beds (C. Reid). Coralline Crag: Gredgrave, 

 Boy ton. Waltonian : Little Oakley. 



Miocene : Touraine, south-west France, Italy, north Germany, Vienna basin. 



Upper Pliocene : Bologna, Alta villa. 



Remarks. — The present species, formerly grouped with Cancellaria, was taken 

 in 1870 by Prof. Sacco as the type of a new sub-genus, Contortia, but he afterwards 

 adopted M. Cossmann's view that it should be referred to the Merica of Adams. 



There can be little doubt that the shells here figured as M. contorta agree with 

 that reported by Wood in 1872 {op. cit.), though with some hesitation, under 

 that name, an identification since adopted at Jermyn St. and at the British Museum 

 of Natural History. They correspond fairly well with the C. contorta, of Homes from 

 the Miocene of Vienna and somewhat less closely with Prof. Sacco's figures of that 

 species from deposits of similar age in northern Italy, but they differ considerably 

 from Basterot's type figure. The condition of our fossils shows, I think, that they 

 are not Miocene derivatives but true Crag forms. As M. contorta is reported by 

 Seguenza, however, from the Upper Pliocene of Bologna and Altavilla, there is no 

 valid objection to the view that it may have also existed in the Anglo-Belgian 

 basin at the same period. My specimens present but little sign of derivation. 



As I cannot find anything else with which I can satisfactorily associate our 

 Crag shells I follow Mr. A. Bell in referring them to ill. contorta, possibly as the 

 northern and Pliocene equivalent of a southern and an essentially Miocene form. 



