EVOLUTION 123 
Eolidide have stinging cells, like those of the Jelly- 
fish and Anemones, at the tips of their cerata. These 
creatures are conspicuously marked with what may 
be warning colours, and do not seek concealment. 
Of mimicry proper, in which an animal seeks to 
resemble some surrounding object or some other and 
distasteful congener, some instances are met with 
among the Mollusca, and others will doubtless be 
forthcoming with more careful observation. 
It has been suggested that some of the Land 
Snails, like Clausilia and certain of the Pupillide 
(=Pupide), as well as some Slugs, may derive a 
certain amount of protection from their passing 
resemblance to the fallen leaf-bud scales of trees, 
while some Helices closely simulate the seed-pods 
of the plants which they frequent. One of our 
Common Shore Periwinkles (Littorina obtusata) is 
thought to resemble the air bladders on the seaweed 
(Fucus), among which it dwells. Lamellaria perspicua, 
a tenioglossate mollusc with internal shell lives on 
Ascidians, and in coloration and markings accurately 
reproduces the appearance of the colonies of its 
victims. Conspicuously coloured Nudibranchs like 
Doto coronata and Dendronotus frondosus closely 
resemble colonies of Hydroids among which they 
dwell. Jovunna Johnstoni lives associated with a 
sponge (Halichondria panicea), for the little colonies 
of which it is readily mistaken. Now, Hydroids 
have stinging cells, and the Ascidian in question, as 
