308 PLIOCENE MOLLUSCA. 



Remarks. — The generic name Sveltia is used for a special group of the Can- 

 cel lariidae without umbilicus, the type form being 8. varicosa, Brocchi, described 

 beli >\v. 



Home confusion has existed as to the correct nomenclature of the present shell, 

 which is fairly common in the Waltonian Crag - at Oakley. 



Ft was described in 1 835 by Nyst (op. bit.) as a new species under the name of 

 Cancellaria Jonkairiana, but afterwards, in 1843, identified by him with Voluta 

 (<'<i itcellaria) varicom of Brocchi. In 1881, however, he reverted to his original 

 determination, expressing a final opinion that it was distinct, both from the latter 

 and from C. coronata, Scacchi, to which Wood had referred a similar shell, after- 

 wards described by him as 0. scalaroides. Wood's C. scalaroides and Nyst's C. 

 Lajonleairii may be regarded, I think, as varieties of the same species, the 

 principal difference between them being that the former is the more slender of the 

 two. I agree with the authorities named that they are specifically distinct from C. 

 varicosa for reasons given in the next paragraph. Both occur in the English 

 Crag, C. Lajonkairii being the most abundant. I have more than 30 examples of 

 the latter, including fragments, from Oakley. One of these I have figured, together 

 with some specimens of it and of 8. varicosa from several localities to show the 

 difference between the two forms. 



One specimen of the present species in the York Museum measures 42 mm. X 

 20 mm. Speaking generally, 8. varicosa is a smaller and more slender shell and less 

 strong and solid. 



Sveltia varicosa (Brocchi). Plate XL, figs. 15 — 17. 



1814. Voluta varicosa, Brocchi, Couch, foss. subap., vol. ii, p. 311, pi. iii, fig. 8. 



1841. Cancellaria varicosa, Bellardi, Desc. Cane. foss. Piem., p. 11, pi. i, figs. 7, 8. 



1856. Cancellaria varicosa, Homes, Foss. Moll. Tert. Wien, vol. i, p. 309, pi. xxxiv, fig. 6. 



1856. Cancellaria varicosa, Beyrich, Zeitschr. Deutsch. Geol. G-esell., vol. viii, p. 579, pi. xviii, fig. 6. 



1871. Cancellaria varicosa, A. Bell, Ann. Mag. Nat. Hist. [4], vol. vii, p. 354. 



1873. Cancellaria varicosa, d'Ancoua, Mem. Cart. Geol. Ital., vol. ii, p. 227, pi. xii, figs. 7, 8. 



1874. Cancellaria varicosa. Van den Broeck, Ann. Soc. Roy. Malac. Belg., vol. ix, p. 120. 

 1876. Cancellaria varicosa, Seguenza, Boll. R. Com. Geol. Ital., vol. vii, p. 8, no 454. 



1890-4. Cancellaria varicosa, Sacco, Boll. Soc. Geol. Ital., vol. ix, p. 264, no. 3867, 1890 ; Sveltia varicosa 



and var. simplicior, Moll. Terr. Terz. Piem., pt. xvi, pp. 54, 55, pi. iii, figs. 42, 43, 1894. 

 1899. Sveltia varicosa, Cossmann, Ess. Paleoconch. compar., vol. iii, p. 20, pi. i, figs. 19, 20. 



Specific Characters. — Differs from S.Lajonhairei in size and texture, in its elongate 

 and more slender spire, and in having fewer ribs ; the transverse sculpture is finer 

 than that shown in Wood's unworn specimen of C. scalaroides from the Coralline 

 Crag (Mon. Crag Moll., pt. ii, pi. xxxi, fig. 9), with which, as just stated, I 

 identify the first-named shell. In 8. varicosa the whorls are more regularly convex, 



