510 PLIOCENE MOLLUSOA. 



Specific Characters. — Shell ovato-globose, thick and strong; generally larger 

 than the typical T. affinis, covered by numerous transverse ridges more or less 

 interrupted by a distinct longitudinal sulcus, outline rounded at both ends, not 

 projecting. 



Dimensions. — L. 16 — 20 mm. B. 14 — 17 mm. 



Distribution. — Not known living. 



Fossil : St. Erth. Coralline Crag : Sutton, Gredgrave, Boyton. 

 Red Crag — Waltonian to Butleyan (passim). Scaldisien, Poederlien : Belgium. 



Miocene : Italy, France — Touraine. Pliocene : France — Gourbesville. 



Bemarlcs. — What I regard as the typical T. aveUana is a large, wide and strong 

 shell with a sulcated back, the upper part having a flattened outline. It has been 

 separated from T. affinis by the transverse ridges being continuous across the 

 sulcus, while in the latter they are said to be thickened, irregular and discon- 

 tinuous, but this is an irregular characteristic. The two shells are allied, but they 

 seem to be most easily separated by their form, size and general appearance. 

 Similar fossils occur in the Italian Miocene, and, according to Lyell, in the 

 Faluns of Touraine. 



Trivia affinis (Dujardin). Plate XLV, figs. 12, 1-3 (contmued from Vol. I, p. 50). 



1870—98. Gyj^rfca affinis, A. Bell, Journ. de Conch., vol. xviii, p. 349, no. 313, 1870; C. (Trivia) 

 enropcea, var. affinis, Trans. Roy. G-eol. Soc. Cornwall, vol. xii, p. 136, 1898. 



1871. Cyprsea avellana, var., Jeffreys in Prestwich, Quart.. .Touru. Greol. Soc, vol. xxvii, p. 143. 



1872. Cyjyrxa (Trivia) affinis, Von Koenen, Mioc. Nord-Deutsch. Moll. -Fauna, vol. i, p. 122, no. 140. 

 1872. Cyprxa affinis, A. and E. Bell, Proc. Geol. Assoc, vol. ii, p. 203. 



1875. Trivia affinis, DoUfus, Etud. Terr. tert. Cotentin, vol. vi, p. 367. 



1878. Trivia affinis, de Stefani e Pantinelli, Boll. Soc. Malac Ital., vol. iv, p. 138. 



1886. Trivia affinis, Dollfus et Dautzenberg, Feuille des Jeunes Natiir., vol. xvi, p. 205. 



1890. Cyprsea avellana, var., C. Reid, Plioc Dep. Brit., p. 243. 



1914. Trivia affinis, F. W. Harmer, Plioc. Moll. Gt. Brit., vol. i, p. 50. 



Specific Characters. — Smaller, narroAver and more elongate than T. aoelhwn, the 

 transverse ridges being finer and less regular. 



Dlmensio7is. — L. 15 mm. B. 10 — 12 mm. 



Distribution. — Not known living. 



Fossil: St. Erth. Coralline Crag: Sutton. Waltonian: 

 Walton-on-Naze, Little Oakley. Newbournian : Sutton, Waldringfield, Felixstowe, 

 Shottishara. 



Miocene : France — Touraine, Germany, Italy, Vienna basin. Pliocene : Biot, 

 Siena, Asti, Gourbesville. 



Remarhs. — This species is allied to T. avellana, and was considered to be a 

 variety of it by Jeffreys. It is, however, not so globose and more elongate, as 

 shown in my plate and in the specimen figured by Wood. It does not seem to be 

 so common in the Crag as I supposed when writing my notice of it in the first 

 volume of this work, and it is not a Pleistocene species as there stated. 



