108 IIELICID^. 



P. suBSTKiATA, JeftVeys. 



Dextral, very minute, striated ; whorls much rounded ; mouth 

 with six teeth (four alone are easily perceptible) of which two 

 are parietal. 



Plate CX XX. fig. 3. 



Turbo sexdenta/us, Mont. Test. Brit. p. 337, pi. 12, f. 8 (not young) ; Maton 



and Rack. Trans. Linn. See. vol. viii. p. 183. — Turt. Conch. 



Diction, p. 221. — Dillw. Recent Shells, vol. ii. p. 879. 

 Vertigo semlentata, Turt. Manual L. and F. W. Shells, p. 103, pi. 7, f. 84. — 



Brown, Illust. Conch. G. B. p. 41, pi. 14, f. 8. 

 Pupa ,, Alder, Trans. Nat. H. Soc. Northumb. vol. i. p. 34. 



Al(ea sulis/riata, Jeffreys, Trans. Linn, Soc. vol. xvi. p. 515. 

 Vertigo ,, Ai.der, Mag. Zool. and Bot. vol. ii. p. 112.— Gray, Manual 



Land and F. W. Shells, p. 202, pi. 7, f. 84. — Thompson, 



Ann. Nat. Hist. vol. vi. p. 114. 

 PnjKt ., Alder, Trans. Nat. H. Soc. Northumb. vol. ii. p. 339. — L. 



Pfeif. Monog. Helic vol. ii. p. 363. 

 Vertigo ciirtu, PIeld, Isis, 1837, p. 304. 



Shell minute, cylindraceous, or oblong-cjlindraceous, 

 .somewhat glossy, a little translucent, tawny, or yellowish 

 horn-coloured (more rarely of a pale olivaceous tint), regu- 

 larly striated longitudinally and rather obliquely. Whorls 

 nearly five, well rounded, i-ather high, enlarging moderately 

 and with tolerable regularity, the penult bulging a little 

 beyond the others ; spire obtuse. Aperture rather sinu- 

 ated, obliquely subpyriform, occupying rather less than one- 

 third of the entire length of the shell, slightly expanded 

 and margined, somewhat indented externally a little above 

 the middle, armed with six deeply seated and mostly pli- 

 ciform teeth, of which two are parietal (lying on the space 

 between the outer and pillar lips), two columellar, and 

 two palatal (or inside the outer lip). Of these, the upper 

 or posterior palatal being very small, and the lower or 

 anterior columellar denticle at times being almost imper- 

 ceptible, four alone arc generally visible to lenses of ordi- 

 nary power. Perforation indistinct. 



