50 BRITISH MOLLUSKS. 



Helix lenticula, Held (1837), Isis, p. 304. 



Polita nitidiosa, Held (1837), Isis, p. 916. 



Helicella nitidiosa, Beck (1837), Ind. Moll. p. 6. 



Zonites purus, Gray (1840), Turt. Man. p. I7l.pl. iv. f. 43. 



Zonites ( Aplostoma) purus, Moquin-Tandon (1855), Hist. Moll, vol. ii. p. 



87. pi. 9. f. 22 to 25. 

 Sab. Northern and Central Europe. Throughout Britain (in woods). 



A small transparent greenish glassy shell, of which, the animal is 

 described by its discoverer, Mr. Alder, as being white with two 

 black cervical lines, with the mantle also white, speckled with black. 

 The shell is rather broadly umbUicated, composed of from three and 

 a half to four whorls, impressed at the sutures, and slopingly 

 rounded towards the periphery. Z. radiatulus, which, in my mono- 

 graph of Helix in Conch. Iconica, I quoted erroneously as a variety 

 of this species, is sculptured with fine radiating stria?, and has a 

 more contracted umbilicus. 



Until within the last few years Z. purus was only found in the 

 northern parts of France and England ; it has now been collected 

 pretty generally in Britain, and on the Continent, from Siberia to 

 Switzerland. 



5. Zonites radiatulus. Finely rayed Zonites. 



Shell ; moderately umbilicated, rather depressly orbicular, greenish 

 glassy, spire convex, sutures a little impressed, 

 whorls three and a half to four, rounded, radiately 

 finely striated, the last whorl somewhat produced ; 

 aperture broadly obliquely lunar. 



Helix nitidula var., Draparnaud (1805), Hist. Moll. p. 117. 



pi. viii. f. 21, 22. 

 Helix striatula, Gray (1821), Lond. Med. Repos. vol. xv. p. 239 



(not of Linnaeus, Miiller, nor Eabricius) . 

 Helix radiatula, Alder (1830), Trans. Nat. Hist. Soc. North- 



umb. vol. i. p. 38, and vol. ii. p. 340. 

 Zonites radiatulus, Gray (1840), Turt. Man. p. 173. pi. xii. f. 137. 

 Helix pura, var., Pfeiffer (1848), Mon. Hello, vol. i. p. 96. 

 Zonites (Aplostoma) striatula, Moquin-Tandon (1855), Hist. Moll. vol. ii. 



p. 86. pi. ix. f. 19 to 21. 

 Hah. Central Europe. Throughout Britain. United States. (Among moss 



and under stones). 

 This well-marked species has been confounded by Pfeiffer and 



