204 
COLOUR IN NATURE 
CHAP. 
associated with a sculpturing of the shell. Accord¬ 
ing to the Countess Maria von Linden, both the 
sculpturing and the colours show a definite orderly 
progression in which phylogeny and ontogeny run 
parallel. In the garden snails, Helix nemoralis and 
H. hortensis , there is an extraordinary amount of varia¬ 
tion in the bands, but nothing is known of the reason. 
Vertebrates .—So far we have seen that colour- 
patterns are best developed in animals in which 
there is a distinct segmentation of the body, that in 
unspecialised forms they show a direct relation to 
the segments, but that as specialisation proceeds, 
they tend to lose this simple and direct relation. 
When we pass upwards to Vertebrates, we find that 
an apparent relation to segmentation is completely 
lost. It is true that in the case of the ringed snake, 
as we shall see, there appears to be a direct relation 
between the ornamentation and the arrangement of 
the cutaneous blood-vessels, and these may well have 
a segmental significance, but at the same time the 
statement on the whole is true that a direct relation 
between the markings and the segmentation of the 
Vertebrate body is no longer obvious. In the general 
case the pattern in a Vertebrate dominates the whole 
organism and is not produced by the repetition of 
one colour scheme. This is perhaps an advance due 
to the perfect synthesis of the body, just as the 
frequent striking difference between the fore and 
hind wings of a butterfly is an advance when com¬ 
pared with the segmental patterns of caterpillars ; 
or it may be an indication that the segmentation of 
a Vertebrate is in essence a different thing from that 
of a worm or an insect. 
