96 
VARIATION IN BANDING. 
Fig. 193 — //. ca/>cf'ata Mont.. 
Perth, 
Collected by Mr. H. Coates, 
Probably largely destroyed )iy 
sheep o\ving to its indefinite and 
protective colouring. 
Fig. 101. — Ili'Ux cnpcratn 
var. ornata Picard, 
Afton Downs, Isle of Wight, 
Collected by Mr. Chas, Ashford, 
Probably avoided by the sheep, 
the distinct markings enabling 
the shells to be easily perceived. 
Rev. S. Spencer Pearce, on tlie contrary, attributes tlie development 
of distinct banding, in species sncb as Ilellx' 
caperata, to the greater visibility of the 
shells so marked to those with mottled or 
indistinct markings, as he found that the 
strongly banded variety ornata pre- 
ponderated in the places fed over by sheep, 
which he therefore assumed perceived and avoided the striped form, 
whose markings would thns appear to be 
of a warning or aposematic character, while 
probably destroying many of the less con- 
spicuous, indistinctly banded specimens. 
In the hedge-rows and other places not 
l)rowsed over by the .sheep, the ordinary 
mottled form prevailed and the distinctly striped variety was com- 
paratively rare. 
Some species have normally a definite nnmber of bands, the gronp 
Pimtataiua, to which Ih'Vt.r ni'moraViif, /nirtrnsls, poinxxfta, and axxprrsxx 
belong is characterized by possessing five bands in the typical form, 
which are very constant in position, tliree being always above the 
periphery and two below it, but they are snl)ject to great modification, 
owing to the absence of one or more of the bands and to their 
coalescence in many and varied combinations. 
Simroth from his study of .slug colouration was led to regard the 
second and fourth bands of the Pexitataoxia as the primitive and 
original pair— corre.sponding to the ancestral mantle-bands of theslngs, 
which are closely connected with the lateral blood .sinuses— wbich, 
by the concentration of their lugment, have ac(piired a lighter border on 
each side, throwing np the third band between them, and each develop- 
ing an additional one outwardl}", the first and the fifth. This view is 
scarcely borne out by tlie acknowledged fact, that the third band in 
Heli.v nemoralh, when present at all, is the band wdiich first appears 
upon the infant shell, and therefore implies for it an eaidier origin 
than for the remainder. 
A convenient method or formula was devised many years ago by 
Herr Georg von Martens to facilitate the tabulation and record of 
the band variations in the Pentatanua, for which pnrpo.ses the 
character of the banding .sbonld always be taken from the last 
whorl of the shell, as the markings .so often vary in character during 
