COLUMBELLA (MITRELLA) SEMICAUDATA. 307 



Columbella (Mitrella) semicaudata (Bonelli). Plate XXXIII, figs. 0, 10. 



1825. Columbella semicaudata, Bonelli, MS. Cat. Mus. Zool. Torino. 



1848. Columbella semicaudata, Bellardi, Mob. Cohimb., p. 8, pi. i, fig. 3. 



1870. Columbella semicaudata, A. Bell, Journ. de Conch., vol. xviii, p. 346. 



1875. Columbella semicaudata, Seguenza, Boll. R. Com. Geol. ltd., vol. vi, p. 276, no. 238. 



1878. Columbella semicaudata, de Stefani e Pantinelli, Bull. Soc. Malac. Ital., vol. it., p. 109. 



1890. Columbella (Mitrella) semicaudata, Sacco, Moll. Terr. Terz. Piem., pt. vi, p. 40, pi. ii, fig. 39; 



Boll. Soc. Geol. Ital., vol. ix, p. 223, no. 2883. 



1901. Mitrella semicaudata, Cossmann, Ess. Paleoconch. com par., vol. iv., p, 236. 



1911. Columbella (Mitrella) semicaudata, Cerulli-Iielli, Palaeont. Ital., vol. xvii, p. 255, pi. xxiii, 



figs. 60-63. 



Specific Characters. — Shell slender with a comparatively narrow base, smaller 

 than M. erythrostoma ; whorls nearly flat, smooth, without spiral sculpture, the 

 last more than half the total length ; spire elevated, diminishing slightly but 

 regularly upwards; suture slight; mouth narrow; outer lip compressed in the 

 middle and nearly straight, rounded below, denticulated within ; canal very short. 



Dimensions. — L. 20 mm. B. 8 mm. 



Distribution. — Not known living. 



fossil: Waltonian Crag : Little Oakley. Lower Pliocene : Biot. 

 Upper Pliocene : Bologna, Asti, Siena, Monte Mario, Val d'Era. 



Remarks. — The imperfect fossil from Oakley here figured appears to corre- 

 spond, so far as it goes, with some specimens of G. semicaudata which I collected 

 some years ago at Asti, as well as with one recently received from Prof. Tssel from 

 the same locality. It shows no sign of the spiral sculpture characteristic of 

 G. sulcata and presents a polished surface, a feature which I have never observed 

 in the case of water-worn examples of the latter species in my Crag collections. 



Columbella (Mitrella) sulcata (J. Sowerby). Plate XXXIII, figs. 13—17. 



1823-5. Buccinum sulcatum, J. Sowerby, Min. Conch., vol. iv, p. 103, pi. ecclxxv, fig. 2, 1823; vol. v, 



p. 122, pi. cccclxxvii, fig. 4, 1825. 

 1842-72. Columbella sulcata, vars. a and j3, S. V. Wood, Ann. Mag. Nat. Hist. [1], vol. ix, p. 539, 



1842 ; Mon. Crag Moll., pt. i, p. 23, pi. ii, fig. 2, 1848 ; 1st Suppl., pt. i, p. 9, pi. ii, fig. 16, 1872. 



1870. Columbella sulcata, S. V. Wood, jmi., and F. W. Harmer, Rep. Sections Brit. Assoc. 

 (Liverpool), p. 91. 



1871. Columbella sulcata, Jeffreys in Prestwicb, Quart. Journ. Geol. Soc, vol. xxvii, pp. 143, 488. 



1871. Columbella sulcata and C. abbreviata, A. Bell, Ann. Mag. Nat. Hist. [4], vol. vii, p. 356; 

 Geol. Mag., vol. viii, p. 453. 



1872. Columbella sulcata and C. abbreviata, A. and R. Bell, Proc. Geol. Assoc, vol. ii, pp. 203, 209, 213. 

 1892. Columbella sulcata, Van den Broeck, Bull. Soc. Belg. Geol., vol. vi (Memoires), pp. 121, 132. 

 1901. Anachis sulcata, Cossmaun, Ess. Paleoconch. compar., vol. iv, p. 238. 



1912. Columbella sulcata, Tesch, Med. v. d. Rijks. v. "Delfstoffeu, pt. iv, p. 78, no. 188. 



