16-i ELEMENTAEY STUDIES IN INSECT LIFE 



which constitute a species are those which do reproduce 

 in kind through successive generations. To ascertain 

 the powers of insects in this direction would be a very 

 difficult task. So for the most part, at present, specific 

 distinctions are based upon characters which, being 

 present in a large number of closely allied individuals, 

 are considered constant. 



Groups of closely allied species are arranged to- 

 gether under one genus ; then closely allied genera are 

 placed in a group called a family; and families with 

 leading characteristics in common form an order; and 

 orders, for the same reason, compose a class ; and classes 

 a branch; and branches a kingdom. This may be 

 termed artificial ; and in part the arrangement is arti- 

 ficial, but the endeavor is to discover the natural group- 

 ing. The classificatory position, then, for instance of 

 our familiar robin, might be sketched thus: 



ANIMAL KINGDOM. 



Branch, Chordata (Vertebrata). Family, Turdidse. 

 Class, Aves. Genus, Merula. 



Order, Passeres. Species, migratoria. 



The term Robin is the common or vernacular name ; 

 the scientific name, the one intelligible to ornithologists 

 of all nations, is Merula migratoria. And so in speak- 

 ing of any one form two names are required, the first 

 to designate the genus, and the second term the species. 

 Varieties are known as subspecies, races, or varieties. 



It will be our purpose to acquaint the student with 

 the principal orders and families of insects, and in so 

 doing the attention is called to the steps to be taken 

 from order and family before species is reached. The 

 system used is an old one, and takes for its basis of 



