306 PLIOCENE MOLLUSCA. 



Genus COLUMBELLA, Lamarck, 1799. 

 Sub-genus MITRELLA, Risso, 1826. 

 Columbella (Mitrella) erythrostoma (Bonelli). Plate XXXIII, figs. 11, 12. 



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



1848. Columbella erythrostoma, Bellardi, Mon. Columb., p. 9, pi. i, figs. 4, 5. 



1870. Columbella erythrostoma, A. Bell, Journ. de Conch., vol. xviii. p. 347, no. 234. 



1875. Columbella erythrostoma, Seguenza, Boll. E. Com. G-eol. Ital., vol. vi, p. 276, no. 245. 



1882. Columbella erythrostoma, S. V. Wood, Mon. Crag Moll., 3rd Suppl., p. 6, p). i, fig. 10b. 



1890. Columbella erythrostoma, C. Reid, Plioc. Dep. Brit., p. 242. 



1890-1904. Columbella (Mitrella) erythrostoma and vars., Saeco, Boll. Soc. Geol. Ital., vol. ix, p. 223, 



nos. 2874-76, 1890; Moll. Terr. Terz. Piem., pt. vi, p. 40, pi. ii, fig. 40, 1890; pt. xxx, p. 93, pi. xix, 



figs. 51-54, 1904. 

 1901. Mitrella erythrostoma, Cossmann, Ess. Pak'ocoucli. compar., vol. i\', p. 236. 

 1911. Columbella (Mitrella) erythrostoma, Cerulli-Irelli, Palaeont. Ital., vol. xvii, p. 256, pi. xxiii, 



figs. 64, 65. 



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

 but little convex, smooth, without spiral sculpture except near the base, the last 

 rather more than half the total length ; spire elevated, diminishing regularly 

 upwards; suture slight; mouth narrow; outer lip compressed and nearly straight 

 in the middle, rounded below, denticulated within ; canal very short. 



Dimensions. — L. 20-30 mm. B. 8-12 mm. 



Distribution. — Not known living. 



Fossil : Waltonian Crag : Walton-on-Naze, Little Oakley. 

 Newbournian : Newbourn. Lower Pliocene : Biot. Upper Pliocene : Asti, 

 Livorno, Monte Mario. 



Remarks. — This species resembles very nearly the Crag form, C. sulcata, 

 described below, but the whorls are not so concave, the suture is slighter, the 

 shape more slender, and except for a few fine inconspicuous ridges at the back of 

 the canal, it is without spiral sculpture. It is possible that in some cases worn and 

 decorticated specimens of C. sulcata may have been mistaken for it. As a guide 

 to collectors, however, I have figured a verified fossil from Asti, which I have 

 received from my good friend Prof. Issel of Genoa, to whom I have been indebted 

 on more than one occasion for similar assistance. I give also an example from 

 Walton which seems to be the same, and I have one or two others, similar, but 

 imperfect, from Oakley. 



The genus Columbella, under which name the Crag forms of the Columbellidse 

 were formerly grouped, has been divided and sub-divided since the publication of 

 Wood's Monograph, the generic and sub-generic terms here used being mostly 

 those adopted by M. Cossmann. 



