166 HELICID^. 



5. Z. radia'tulus*, Alder. 



Helix radiatula, Aid. Cat. Northumb. Moll. p. 13. Z. radiatulus, F. & H. 

 iv. p. 38, pi. cxxi, f. 1 . 



Body dark horncoloiir : tentacles nearly black, the upper 

 ones very slender and the lower pair short : foot exceedingly 

 narrow, pointed behind, its sides marked \^dth minute black 

 specks. 



Shell compressed, equally convex on both sides, very thin, 

 remarkably glossy, semitransparent, dark horncolour, distinctly 

 and beautifully marked across the whorls on the upper side by 

 strong curved and close-set striae which reach the suture, the 

 under side being also marked, but less distinctly, by similar 

 striae : epidermis thin : vjhorJs 41, convex, and very little di- 

 lated laterally, the last occupying rather less than one-half of 

 the shell : sjnre slightly raised : suture moderately deep : mouth 

 nearly round, sometimes thickened inside by a broad but slight 

 white rib : outer lip scarcely oblique : umbilicus narrow, but 

 rather deep, disclosing all the internal spire. L. 0*075. B. 0*15. 



Var. viridescenti-alha. Shell greenish-white. 



Habitat : Under stones, logs of wood, dead leaves, 

 and moss in woods, from the Moray Firth district to 

 Dorset. The variety is from Shropshire, Co. Cork, and 

 Co. Tyrone (J.G.J.) ; Belfast (Thompson). This species 

 is one of our upper tertiary fossils. Malm has recorded 

 it as a Swedish shell, Scholtz as Silesian, Moquin-Tan- 

 don and others from different parts of France, Stabile 

 from Lugano, and myself from the Lower Harz and 

 Switzerland. 



This little moUusk is less shy and inactive than Z. 

 purus, and usually frequents moister places. It re- 

 sembles that species in the size and form of the shell ; 

 but the peculiar sculpture, more glossy appearance, and 

 narrower umbilicus of the present species will easily 

 serve to distinguish it from Z. purus. 



* Slightly rayed. 



