PLEUROTOMA INERMIS. 207 



from that of Denmark. Judging from the figures of P. Sehjsil published by the 

 latter, twenty-four in all, it seems that this species was, in Oligocene times, a very 

 variable one. 



Pleurotoma inermis, Partsch. Plate XXVI, figs. 5, 6. 



184-2. Pleurotoma inermis, Partscli, Neue Aufst. Petr. Samml. K. K. Hof. Min. Cab., no. 960. 



1848. Pleurotoma porreda, S. V. Wood, Mou. Crag Moll., pt. i, p. 55, pi. vii, fig. 1. 



1853. Pleurotoma inermis. Homes, Foss. Moll. Tert. Wien, vol. i, p. 349, pi. xxxviii, fig. 10. 



1872. Pleurotoma inermis, and var. nuda, S. V. Wood, Mon. Crag Moll., 1st Suppl., pt. i, p. 33, 



pi. iii, figs. 2 a, 2 h. 



1896. Pleurotoma inermis, Bernays, Bull. Soc. Beige G-eol., vol. x (Memoires), p. 128. 



1904. Pleurotoma inermis, Sacco, Moll. Terr. Terz. Piem., pt. xxx, p. 42, pi. 11, fig. 47. 



1912. Pleurotoma iiiermis, Tescli, Med, v. d. Rijks. v. Delfstoffen, pt. 4, p. 88, no. 226. 



Specific Gharacfers. — Shell slender, elongato-f usiform ; whorls 9 — 10, distinctly 

 carinate, convex below and concave above the keel, the last more than half the 

 total length ; ornamented in the type by about twelve flexuous longitudinal costte 

 "which are continuous but are sharply reflexed across the shelf and become slightly 

 nodular upon the keel, also by fine impressed strife which extend to the base of 

 the shell ; spire regularly tapering ; apex acute ; suture well-marked ; mouth 

 lanceolate, passing into a long and somewhat twisted canal ; columella tortuous. 



Dimensions. — L. 28 mm. B. 10 mm. 



Distribution. — Not known living. 



Fossil : Coralline Crag : Gomer, Gredgrave, Ramsholt, Boyton. 

 Waltonian : AValton-on-Naze, Little Oakley. 



Miocene: Belgium, Vienna basin, Italy. Diestien (zone a Terebratida grandis) ; 

 Casterlien (zone a Isocanlia cor) : Antwerp. Scaldisien : Holland. 



Remarhs. — This characteristic Miocene fossil is one of the many species which 

 were unknown to Wood from any Crag horizon later than the Coralline Crag, but 

 has been obtained since from Walton by Prof. Kendal and from Oakley by 

 myself. Dr. Tesch has also found it from one of the Dutch borings in beds 

 believed by him to be equivalent to the Scaldisien of Belgium. Wood figures two 

 varieties, one with the zig-zag sculpture characteristic of the type form of this 

 species (PI. XXVI, fig. 5), and another he calls var. nuda (fig. 6), from which such 

 ornamentation is absent. I figure a well-preserved specimen of each of these from 

 the Coralline Crag of the Boyton marshes. 



In his list of Coralline Crag fossils published in Prestwich's paper (Quart. 

 Journ. Geol. Soc, vol. xxvii, 1871, p. 145) Jeffreys identifies the present species 

 with Pleurotoma nivale, Loven, a Recent form ranging from the Portuguese coast 

 to the Arctic circle. Although the sculpture of the latter resembles our shell to 



