86 COLIMACEA. 



the volutions, nearly to the apicial one; aperture slightly lunate, 

 or nearly round. Diameter about a quarter of an inch. 



Discovered near Scarborough by Mr. Bean, and has been 

 found by Mr. Alder in Northumberland ; and Thompson says 

 he has seen but one Irish specimen, which was procured at 

 Dunscombe Wood, near Cork, by Miss King, of Cork. 



Its favourite habitat is timber which has been cut down, and 

 under decayed wood. 



38. Helix pura, pi. IX, f. 15, 16. 



Helix pur a, Alder, Cat., No. 46; lb., Mag. Zool. and Bot., 

 II, p. 108; Thompson, Ann. and Mag. Nat. Hist., VI, p. 32; 

 Turton, Man., p. 59, the description only; Brown, Illust. Conch., 

 p. 53, pi. 18,* f. 11, 12; Helix nitidula, var. /3, Jeffreys, Linn. 

 Tr., XIII, p. 511. 



Variety 1. Shell pale horn-coloured. Alder, Mag. Zool. 

 and Bot., II, p. 108. 



Shell nearly white, depressed, somewhat pellucid, and glossy, 

 a little striated, or wrinkled; body large; spire small, with three 

 volutions, placed somewhat oblique ; base considerably flattened, 

 provided with a large and deep umbilicus ; base never opaque. 

 Diameter between a fifth and sixth of an inch. 



This shell differs from H. crystallina in being larger, more 

 convex, and less glossy ; the volutions are not so closely set, 

 the body somewhat larger in proportion to the spire, with a 

 larger umbilicus, and especially in the fine, regular stria^, of 

 which the H. crystallina is destitute. 



Found near Newcastle-upon-Tyne by Joshua Alder, Esq., 

 and as far as is known, rather a local species in England ; in 

 Ireland, according to Thompson, it is rather widely spread ; 

 its usual habitat being among moss, in sheltered situations. I 

 found it near Cabinteely, County of Dublin. The yellowish 

 horn-coloured variety is most commonly met with. 



Sub-Genus 8 — Trigonostoma. — Ferussac. 



Shell suhdiscoidal ; apex depressed ; base umbilicated; aper- 

 ture trigonal; outer lip denticulated; epidermis Jbr the most 

 part hispid. 



