(590 PLIOCENE MOLLUSCA. 



Waltonian : Walton-on-Naze, Little Oakley. Xewbourniau : Bentley, Newbourn, 

 Felixstowe, Waldringfield, Sutton. 



Miocene : Belgium, Vienna basin. 



Upper Pliocene : Belgium — Casterlien, Scaldisien, Poederlien. 



Remarks. — As stated on p. 689, Prof. Sacco separates this shell from X<tti<-a 

 varians, Duj., proposing for it the specific name exvarimis, which I adopt. 



Messrs. Dollfus and Dautzenberg identify it with N. helicina, Homes (non 

 Brocchi), one of his figures (op. cit., pi. xlvii, fig. 6) being specially similar to the 

 Belgian and Crag shells which are here described under the present name. Some of 

 the principal features of our shell are the large proportion of the body-whorl which 

 remains unconvered above its junction with the outer lip, and its prominent spire. 



Natica (Lunatia) Montagui, Forbes. Plate LV, fig. 10. 



1838. Natica Montagui, Forbes, Malac. Moneusis, p. 32, pi. ii, tigs. 3. 4. 



1846. Natica Montagui, Loven, K. Svensk. Vet.-Akad. Forh., vol. iii, p. 89. 



1853. Natica Montagui, Forbes and Hanlev, Brit. Moll., vol. iii, p. 336, pi. ci, figs. 3, 4. 



1867 — 9. Natica Montacuti, Jeffreys, Brit. Conch , vol. iv, p. 227. 1867 ; vol. v, p. 215, pi. lxxviii, fig. 6. 



1872. Natica Montacuti, S. V. Wood, Mon. Crag Moll., 1st Suppl., pt. i. p. 78, pi. iv. fi--. 10. 



1872. Natica Montagui, A. and R. Bell, Pimc. Geol. Assoc, vol. ii, p. 213 



1873—6. Natica Montacuti, Segueuza, Boll. R. Com. Geol. Ital., vol. iv, p. 352, no. 264. 1873 ; vol. v. 



p. 280, no. 106, 1874; vol.vii, p. 12, no. 491, 1876. 

 1878. Lunatia Montagui, G. 0. Sars, Moll. Reg. arct. Norv., pp. 157, 358. 

 1880. Natica Montacuti, Stewart, Proc. Belfast Nat. Field Club (appendix), p. 174. 

 1890—98. Natica Montacuti, A. Bell, Rep. Brit, Assoc. (Leeds), pp. 413, 420, 1890 ; Trans. Roy. Geo! 



Soc. Cornwall, vol. xii, p. 145, 1898. 

 1890. Natica Montacuti, Cams, Prod. Faun. Medit,, vol.ii, p. 306. 

 1899. Natica Montagui, Locard, Coq. mar. Cotes de France, p. 91. 

 1901. Natica (Naticina) Montagui, Kobelt, Icon, schalentrag. europ. Meeresconch., vol. ii, p 99, pi. Iv, 



figs. 14, 15. 

 1901. Lunatia Montagui, Br^gger, Norges geol. Underso'gelse, No. 31, p. 657, pl. xviii, fig. 22. 



1912. Natica- (Naticina) Montagui, Dautzenberg et Fischer, Camp. Scient., Prince de Monaco, 

 vol. xxxvii (Mollusques), p. 245. 



1913. Lunatia Montagui, (Jdhuer, K. Svensk. Vet.-Akad. Haudl., vol.1, p. 27, pl. iv, figs. 16 — 18. 

 1913. Natica (Naticina) Montacuti, Gignoux, Form. mar. Plioc. et Quater. d'ltal., p. 562, pl. xiii, 



figs. 7,8,9. 



Specific Characters. — Shell small, smooth, fairly solid, globose; whorls 5 — 6, 

 convex, not so rapidly enlarging as in some other species, the last tumid ; spire 

 short, a little elevated, with a blunt apex; suture distinct, slightly channelled; 

 mouth semi-circular, obtusely rounded and expanded below; outer lip incurved 

 upon the body-whorl; inner lip thickened, especially at the base; umbilicus small, 

 open. 



Dimensions. — L. 10 mm. B. 8 mm. 



