12 NATURAL SCIENCE. march, 



assumed that the majority trade upon the unpleasant reputation of 

 the few ; just as the sweet-tasting Pierids are thought to lead com- 

 paratively peaceful lives by imitating the nauseous Heliconidae. 



It is, to our mind, a highly significant fact that cases of mimicry 

 are, to a certain extent, proportionate to the number of species in the 

 group where they occur. Among insects the vast majority of 

 examples are met with ; there are a few only reputed cases of 

 mimicry in the two groups. Birds and Reptiles, and it is difficult to 

 point to one example of advantageous mimicry in the Mammalia, 

 which is the smallest group of the four. There is no a priori reason 

 why mimicry should be less advantageous to a mammal than to an 

 insect. On the contrary, indeed ; for an insect as a rule leads a very 

 short life, and when it has succeeded in laying its eggs, its claims 

 upon life are exhausted. Natural Selection, as it has been said, cares 

 nothing for the individual ; she only concerns herself with the race. 

 Merely from the point of view of the continuance of the race, it seems 

 hardly necessary for a butterfl}' to have any assistance in prolonging 

 its life; pairing takes place so soon. In fact, in some Lepidoptera 

 the impatient males wait round the cocoon for the emergence of their 

 mate. On the other hand, a mammal which has to live for a long 

 time before being able to reproduce its kind, and is frequently 

 preyed upon by many other creatures, both mammals and birds, 

 seems much more entitled to the protection afforded by such a device 

 as mimicry ; so, too, with birds and reptiles. 



Considering the immense multitude of insects, and tht- daily 

 increase in our knowledge of hitherto unknown species (no less than 

 1,500 new species of Lepidoptera are recorded in the Zoological 

 Record for i88g as having been described during that year), and 

 considering also the comparatively few plans of coloration that are 

 met with, it would not be at all surprising to meet with accidental 

 resemblances. The larger the amount of material, the larger would 

 the number of accidental resemblances be; and this is precisely what 

 we find. 



Of more importance than purely fortuitous likenesses, supposing 

 that such exist, are the resemblances due to similar conditions. 

 Andrew Murray laid weight upon these little understood causes in 

 attempting an explanation of the phenomena of mimicry. Dr. Seitz 

 has lately discovered some curious instances, which seem to be only 

 explicable on such a theory. In a forest of Southern Brazil, this 

 naturalist found a perfectly circumscribed region, inhabited by insects 

 almost entirely blue in colour ; a few miles away from this spot the 

 insects were red, yellow — any colour but blue ; but in the particular 

 area blue was so characteristic a tint that out of twenty butterflies 

 ten were entirely blue and the remaining ten partially blue. Another 

 equally remarkable instance of an apparent connection between colour 

 and locality has been longer known. Ransonnet, in his work upon 

 Ceylon, gives two beautiful plates representing life on a coval reef. 



