TURBONILLA (PYRGOSTELIS) TENUISSIMA. 571 



1901. Pyrgosfelis scalaris, var. rufescens. Conch. Soc. List, Jouru. of Conch., vol. x, p. 20. 

 1905. Parthenina (Pyryostelis) rufescens, Kobelt, Icon, schalentrag. europ. Meeresconch., vol. iii, 

 p. 130, pi. Ixxi, figs. 19, 20. 



Specific Gliaritctcis. — Shell slender, elongate, rather thin ; whorls 8 — 10, convex, 

 not angulated ; ornamented l)y numerous fine inconspicuous longitudinal costae 

 closely crowded together, wliich do not reach the base, with fine spiral lines 

 extending to it ; spire regularly diminishing upwards to a fine point ; suture deep, 

 slightly oblique; mouth oval, angulate above, rounded below; outer lip somewhat 

 expanded, incurved above ; inner lip thickened and reflected Ijelow ; umliilicus none. 



Dimensions. — L. 5 — 7 mm. B. 1 — 1*5 mm. 



Distribution. — Recent: Lough Strangford, co. Antrim, Alierdeenshire, west 

 coast of Scotland, Hebrides. Scandinavian coasts — Finmark, Bohusliin. 

 Fossil : Coralline Crag (Jeffreys). Selsey. 



Eemarlcs. — This shell, which is nearly allied to T. rufa, although it is shorter 

 in the spire and its sculpture is much finer and less conspicuous, has been regarded 

 by Jeffreys and some other recent authorities as a variety of T. scalaris, but this 

 view has not been imiversally accepted. It differs from the latter both in form 

 and sculpture, the whorls are convex, not angulate as in that species. 



The subgenus Fi/rgostelis was proposed by the Marchese di Monterosato in 1884 

 to include T. rnfa and some allied forms having fine ridges in the intercostal spaces ; 

 by Kobelt it has been grouped with Parthenina, while in the Conchological Society's 

 list it is regarded as a variety of Pyrgostelis scalaris. 



The specimen here figured is from the York Museum, where it Ijears the name 

 of Odostomia rufescens. 



Turbonilla (Pyrgostelis) tenuissima (Etheridge and Bell, MS.). Plate XLIX, 



fig. 42. 



1898. Chemnitzia tenuissima, A. Bell, Trans. Eoy. Geol. Soc. Cornwall, vol. xii, p. 148. 



Specific Characters. — Shell minute, slender, turreted; whorls 7 or 8, slightly 

 convex, gradually and regularly enlarging ; spire elongate, tapering to a com- 

 pressed point ; ornamented by excessively fine and numerous longitudinal ribs, 

 crowded together, and by very delicate spiral ridges ; suture clearly marked, but 

 not deep ; mouth narrow, short, angulated above ; outer and inner lips forming a 

 thin, continuous peristome. 



Dimensions. — L. o mm. B. 1 mm. 



Distribution. — Not known living. 

 Fo.ssil : St. Erth. 



Bemarl-s. — This delicately sculptured little shell, one of the smallest of the 

 group reported by Mr. Bell from St. Erth, is regarded by him as new and at 

 present unique. It comes from the Warburton Collection at the British ]\Iuseum. 

 The sculpture is but indistinctly shown, even when examined under a microscope. 



