I0O HULL SCIENTIFIC AND FIELD NATURALISTS’ CLUB. 
isolated species, will be captured at the same time. These 
two are representatives of an older fen fauna which has dis- 
appeared with the Holderness meres. They are not found in 
the recently formed fen at Kelsey Hill, 
H. evicetoyvum is well established on the Humber bank at 
Paull, in the achatina locality, and for a short distance by the 
side of the Seaton Road at Hornsea—the two places being 
more than twenty miles apart. It is curious that these two 
should be associated in the only other achatina locality in the 
East Riding—Drewton. 
The beautiful Helix virgata, var. hyalozona is confined to a 
small area on the cliff top, south of the Skipsea lacustrine 
deposit. Why does it not spread further south? Suppose 
two or three wandered away and interbred with the ordinary 
form (as they do at Hunstanton, where /yalozona is more 
abundant) which form would they produce? I commenced 
an experiment with the object of deciding this problem 
with Helix aspevsa, vars. minor, and exalbida (from the 
Hornsea colony), which were taken in May and kept 
apart through the winter. I succeeded in hatching a 
large number of eggs from both, but all my trouble was 
wasted through the inquisitiveness of a boy who could not 
understand why snails were kept under glass, and thought 
they would thrive better in the garden. As far as I could 
judge from specimens two months old (August), all were 
going to be the ordinary colour. However, if exalbida ever 
occurs at Hedon, it may safely be reckoned one of my 
escapes, and in that case, my surmise will be proved 
incorrect. At present, I believe that this gives the reason 
why the Skipsea /iyalozonw does not spread, and accounts for 
the want of increase of evalbida at.Hornsea. Recent building 
and subsequent gardening operations have probable extermin- 
ated the latter altogether. 
Helix cantiana was formerly supposed to be confined to the 
four metropolitan counties,“ but it is a very common 
shell in Holderness, especially between Hedon and Burstwick, 
where it may be found in profusion on the roadside. I found 
great difficulty in procuring specimens with the thickened rib 
which takes the place of the usual helix lip. Do they die in 
the second year ? 
H. capevata, which occurs on gravel at Kelsey, Paull, Spurn, 
&c., illustrate one mode of shell distribution by appearing on 
the railway bridge over the Burstwick drain, the top of which 
is covered with gravel from Kelsey. 
* Gray’s ‘‘ Turton,” 1857, p, 139. 
