26 EVOLUTION AND GENETICS 



still used with modifications employs for this succession of groups 

 the following terms, beginning with the initial subdivision of 

 living things into plant and animal kingdoms and proceeding 

 through those of decreasing extent: 



Kingdom 

 Phylum 

 Class 



Order 



Family 

 Genus 



Species 



Thus man is Homo sapiens — the species sapiens of the genus 

 Homo, which ])clongs to the family Hominidae in the order Pri- 

 mates. The Primates are members of the class Mammalia, in the 

 phylum Chordata of the animal kingdom. To indicate finer dis- 

 tinctions in classification such modifications as suborders and 

 superfamilies are sometimes used. In the example given every- 

 thing up to the ordinal name indicates man's exalted opinion of 

 himself, for he stands alone! The order, however, acknowledges 

 his association with the apes and monkeys, the class, to all animals 

 that have hair and nourish their young with milk, the phylum to 

 those which have a backbone and to certain other remote rela- 

 tives, and the kingdom, finally, to all animals. 



Mimicry. Superficial resemblance is usually but not always 

 a dependable index of relationship. We have mammals which may 

 be mistaken for fish, beetles and flies which look like wasps, flies 

 that resemble bumble bees, and a variety of lesser resemblances. 

 Such abnormal superficial similarity has been recognized as play- 

 ing a definite part in the lives of organisms, and the gradually 

 accumulated knowledge represented by modern classification has 

 relegated these types of resemblance to their proper places and 

 expressed the fundamental relationship which they often obscure. 

 The superficial resemblance of one species to another is called 

 mimicry. This is well illustrated by the resemblance of certain 

 harmless species of insects to others which are either unpalatable 

 to bird or animal enemies, or able to defend themselves. The 

 common eastern butterfly, Basilarchia archippus (Cram.), while 

 superficially very different in appearance from its congeners, is 

 much like the milkweed butterfly, Danaus menippe (Hbn.), which 



