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COLOURS AND COLORATION IN ANIMALS. SEPT., 1892. 
If the theory is true, then bright colours are still of 
warning significance, though not produced for that special 
purpose. Dr. Eisig’s conclusion is supported by experiments 
which have been made with nudibranch molluscs. Among 
these animals are species protected by coloration, which is, 
however, brilliant, while the animals themselves are 
unpalatable. 
With regard to the so-called mimicry of unpalatable by 
palatable forms, Mr. Beddard suggests various difficulties. 
The Danaidce, themselves an uneatable race of butterflies 
and models for mimicry, resemble in South America the 
uneatable Heliconidce. This resemblance is believed not to be 
a case of mimicry, but due to the need that types of warning 
colours may be as few as possible, so that enemies may have 
as little as possible to learn, and thus are less likely to make 
mistakes. Now it is well known that some of the Pieridce , or 
“ Whites,” closely resemble certain Heliconidce, the explanation, 
according to the late Mr. H. W. Bates, being, as mentioned 
above, that the former are palatable, and, therefore, by their 
resemblance to the latter, obtain the reputation of being 
unpalatable. But Mr. Beddard suggests that the principle 
which has just been stated with regard to the Danaidce may be 
applicable to the mimicking Pieridce, for two genera of that 
family are provided with organs similar to those of the 
Heliconidce, which secrete a strongly odorous substance sup¬ 
posed to be the cause of their immunity from attack ; and 
Leptalis, one of the mimicking genera, actually gives off an 
odour disagreeable to human noses. 
Again, there are various other forms of lepidoptera which 
resemble each other as much as in cases of so-called mimicry, 
yet for no apparent reason. Such is the resemblance between 
various North American species of the genus Catocala, which 
resemble the “ Yellow Underwings ” of the genus Triphcena. 
A similar difficulty occurs in the case of animals which 
resemble each other, but live in countries far apart, such as 
the New Zealand Cuckoo and American Hawk, which are 
much alike. The former is quite unlike the hawk of its own 
country. 
In two other cases of difficulty brought forward by 
Mr. Beddard, we can perhaps see some explanation. The one 
case is of two beetles, very much alike, which feed on the 
nettle, one being very rare, the other common, both minute. 
The author asks whether, supposing the rare form is 
palatable and the common one unpalatable, any benefit is 
gained, as surely protection is obtained by the minute size. 
Then, again, there is a most remarkable resemblance between 
an ampliipod crustacean and a medusa. According to the 
