NASSA PRISMATICA. 65 



Remarks. — This rather variable sliell, Avliich is exceedingly common in the 

 Pliocene deposits of St. Erth in Cornwall, was recorded under the name of A'. 

 fierrata by S. V. Wood, jun., in 1885, and by Prof. Kendall and Mr. R. G. Bell in 

 1886. It differs essentially, however, from the Italian form of that species, being- 

 larger and stronger, with much coarser sculpture, the longitudinal costse and the 

 spiral striations being fewer in number and distinctly tuberculate at the point of 

 intersection.^ Some specimens attain a length of 40 mm. or more. Messrs. 

 Etheridge and A. Bell, considering it worthy of specific rank, have called it N. 

 semirelicosa. I have figured two shells from St. Erth for the purpose of comparison, 

 the smaller of the two, var. minor (PI. Ill, figs. 12, 13), corresponding closely with a 

 specimen from the Coralline Crag of Boyton in the Reed collection at York. I have 

 another from Oakley, not quite perfect, which seems the same ; it differs from * 

 the other Nassas of that locality in the coarseness of its sculpture. 



Nassa prismatica (Brocchi). Plate III, figs. 1, 2. 



1814. Briccinum 'prysmathicmn, Brocchi, Coiicb. foss. subap., p. 337, pi. v, fig. 7. 



1856. Buccinum prismaticum. Homes, Foss. Moll. Tert. Wien, vol. i, p. 146, pi. xii, fig. 13. 



1870. Nassa prismatica, A. Bell, Jouru. de Conch., vol. xviii, p. 345. 



1875. Nassa prismatica, Seguenza, Boll. E. Com. G-eol., vol. vi, p. 278. 



1882. Nassa prysmatliica, Bellardi, Moll. Terr. Terz. Piem., pt. iii, p. 71, pi. v, fig. 1. 



1901. Nassa (Uzita) prismatica, Cossmann, Ess. Paleoii. comp., pt. iv, p. 205, pi. ix, figs. 4, 5. 



1911. Nassa {Uzita) limata, Cerulli-Irelli, Faun, malac. mariana, pt. v, p. 248, pi. xl, figs. 4, 8. 



Specific Characfprs. — Shell turreted ; spire more or less elongate ; apex acute ; 

 whorls convex, depressed above, the last comparatively short, rather less than half 

 the total length; suture deep; longitudinal ribs 12 — 18, narrow, prominent, sul)- 

 acute, straight on the upper whorls, oblique or sinuous on the last, extending to the 

 base of the shell ; spiral costae distinct, narrow, imdulating, uniform, hardly 

 equalling the spaces between them ; apex acute ; mouth suborbicular, angulate 

 above, Avith a small notch, expanded at the base ; outer lip slightly thickened 

 outside, plicate within; inner lip covering but not wholly adherent to the columella ; 

 columella deeply excavated in the middle ; canal notched, wide and open, turning 

 sharply to the left. 



Dimensions. — (Of the Crag specimen) L. 26 mm. B. 14 mm. 



Distribution. — Recent : Adriatic. 



Fossil : Coralline Crag. Waltonian : Little Oakley (possibly else- 

 where in the Red Crag). 



Pliocene : Italy, Sicily. 



Remarks. — There seems to be considerable difference of opinion as to this 

 species, some authorities regarding it as equivalent to the Recent Mediterranean 



' Compare with this PI. Ill, fig. 6 of the present work. 



