170 HELICID^. 



Menke having been made in the same year, I trust T may 

 be pardoned in indulging a patriotic feeling and giving 

 the precedence to my own countryman, especially as the 

 name proposed by Menke designates a variety and not 

 the species. 



It differs from its nearest ally, Z. nitiduSy in its less 

 prominent spire, more compact whorls, much stronger 

 striae, deeper suture, and more open umbilicus. 



8. Z. crystal'linus*, Miiller. 



Helix crystallina, Miill. Verm. Hist. pt. ii. p. 23. Z. crystalUnus, F. & H. 

 iv. p. 41, pi. cxxii. f. 1, 2. 



Body clear greyish- white, nearly transparent: tentacles rather 

 short ; upper pair ebony-black, coloured by the retractor nerve ; 

 lower pair grey : foot narrow, pointed behind, whitish. 



Shell depressed, more convex below than above, thin, very 

 glossy and iridescent, transparent, greenish-white or hyahne 

 like glass, very finely and closely striate transversely, espe- 

 cially towards the suture : epidermis very thin : whorls 4^5, 

 rather convex, but compressed outwards, increasing gradually 

 in size : spire not much raised : suture slight, but distinct : 

 7nouth semilunar, sometimes strengthened inside by a slight 

 <rib, which is seen through the shell : outer lip obhquely set, 

 very thin : umbilicus narrow and only exposing a small part 

 of the penultimate whorl. L. 0*065. B. 0*125. 



Var. complanata. Shell nearly flat on both sides ; the last 

 whorl proportionally larger than the others. 



Habitat : Under stones and decayed pieces of wood, 

 as well as among dead leaves and moss, in woods and 

 shady places, from the Moray Firth district to Guernsey. 

 The variety w^as found by me in Leigh Woods nearBristol. 

 This species is one of our upper tertiary fossils. Its 

 foreign distribution is very extensive, and ranges from 

 Finland to Algeria and Sicily, as well as to Madeira and 

 the Azores. 



* Like crystal. 



