LITTORINA OBTUSATA. 661 



1896. Litorina rudis, var. tenebrosa, Munthe, Bull. Ceol. Inst. Upsala, vol. ii, p. 3. 



1908. Littorina saxatilis, var. tenebrosa, Kobelt, Icou. schalentrag. europ. Meerescouch., vol. iv, p. 61, 



pi. ex, figs. 7, 8; pi. cii, fig. 22. 

 1910. Littorina rudis, var. tenebrosa, 0yen, K. Norske Vid. Selsk. Skrift., No. 9, p. 33. 

 1912. Littorina saxatilis, var. tenebrosa, Dautzenberg et Fischer, Camp. Scient., Prince de Monaco, 



vol. xxxvii (Mollusques), p. 194, pi. ix, figs. 13, 14. 

 1915. Litorina rudis tenebrosa, Johnson, Bost, Soc. Nat. Hist., vol. vii, Occ. papers, Fauna of 



New England, no. 13, p. 123. 



I arietal Characters. — Shell ovato-conical, generally of a dark colour, not very 

 thick ; whorls 5, more or less convex ; spire elevated ; spiral sculpture indistinct 

 or obsolete ; apex acute; mouth ovate. 



Dimensions. — L. 12 — 18 ram. B. 10 — 12 mm. 



Distribution. — Recent : British coasts, estuarine (Jeffreys). French coasts, 

 littoral (Locard), Canada, New England. 



Fossil : Butleyan Crag : Butley. Icenian : Bramerton. Litorina- 

 beds, Sweden, Tapes-banks, Christiania ; Trondhjem. 



Remarks. — Several forms have been described and figured under this name by 

 the authors quoted above ; in some cases the suture is deep, in others less so ; in 

 one variety (elata) the spire is elongate, in another, regarded by MM. Dautzenberg 

 and Fischer as more typical, it is rather short. Locard says that in the recent 

 shell the colour is variable, usually dark; specimens from the Crag are generally 

 ferruginous. 



'&' 



Var. tenebrosa elata, Dautzenberg and Fischer. Plate LIII, fig. 19. 



1912. Littorina saxatilis, sub.-sp. tenebrosa, var. elata, Dautzenberg et Fischer, Camp. Scient., Prince 

 de Monaco, vol. xxxvii (Mollusques), p. 194, pi. ix, fig. 15. 



Specific Characters. — Agrees with what the above authorities regard as the 

 typical var. tenebrosa, but it has a longer spire. 



Dimensions. — L. 15 mm. B. 10 mm. 



Distribution. — Recent : Iceland, south Coast. 



Fossil : Icenian Crag : Bramerton, Bulchamp, Beccles, Easton 

 Bavent, Yarn Hill. 



Pleistocene : Selsey, Largo Bay, estuarine clays of Belfast. 



Remarks. — The recent specimen here figured for comparison is from the 

 Holmes Collection ; in most of those described by the authors named above the 

 spire is more or less elongate. 



Littorina obtusata (Linne). Plate LII, figs. 27—29. 



1758. Turbo obtusatus, Linne, Syst. Nat,, eel. x, p. 761, no. 526. 



1846. Litorina obtusata, Loven, K. Svensk. Vet.-Akad. Forh., vol. iii, p. 94. 



1853. Littorina littoralis, Forbes and Hanley, Brit. Moll., vol. iii, p. 45; vol. iv, pi. lxxxiv, figs. 5—7. 



1859. Littorina littoralis, G-. B. Sowerbv, 111. Ind. Brit, Shells, pi. xii, figs. 20, 21. 



86 



