134 PKARCE : VARIETIES OF BANDED SNAILS. 



On the sand-hills which lie between Burnham and the mouth 

 of the river Brue, the proportion in which the varieties of 

 H. caperata occurred was : — 



5 individuals of the var. oniata, to 

 85 ,, „ „ mottled form. 

 With them were associated Helix virgata and Bulimus acutus. 



On the other side of Burnham, northwards to Berrow 

 Church, the sand-hills yielded an even more striking proportion 

 between the two varieties : — 



I individual of the var. ornata, to 

 66 „ „ „ mottled form. 



Among the eighty-five and sixty-six mottled forms just 

 mentioned, thirty-two and one, respectively, of them are of the 

 the variety //^/z/^?, having a unicolourous dark brown hue, which 

 makes them appear very different to the ordinary mottled forms. 

 But I have classed them thus, since the uniformity of dark 

 colouring has evidently come about from the expansion and 

 running together of the darker blotches, till the whole shell has 

 become suffused. In the variety nigrescens of Helix virgata, 

 we are presented with an analogous case. 



Though I have no evidence to the point, it would not be 

 much of a surprise to me should we find out, eventually, that 

 both these dark varieties, the yyc.fulva oi Helix caperata and var. 

 nigrescens oi Helix virgata, are really reversions, backwards, from 

 mottled forms to some ancestral form with a wholly brown 

 shell. The casual manner and out-of-the-way localities in 

 which both these varieties turn up, would seem perhaps, to 

 point to this conclusion. 



Localities for the (a) var. fulva of Helix caperata and (b) 

 var. nigrescens of Helix virgata. 



(a) On chalk down (bleak and barren) in Firle Beacon, 

 Sussex, 1881. On sand-hills near Burnham, Somersetshire, 

 1888. A very near approach to this var. from Shaldon, near 

 Teignmouth, South Devonshire, 1888. 



J.C, vi., Oct., 1889. 



