170 HELICID.E. 



Menke having been made in the same year, I trust I 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. nitidus, in its less 

 prominent spire, more compact whorls, much stronger 

 striae, deeper suture, and more open umbilicus. 



8. Z. CRYSTAL'LINUS*, Miiller. 



Helix crystallina, Mull. Verm. Hist. pt. ii. p. 23. Z. crystallinus, 

 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 

 hyaline like glass, very finely and closely striate transversely, 

 especially 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 : mouth semilunar, sometimes strengthened inside 

 by a slight rib, which is seen through the shell : outer lip 

 obliquely 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 was found by me in Leigh Woods near Bristol. 

 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. 



