30 HUMBLE CREATURES. 



another, to which it is allied by less powerful links. 

 In treating of it per se, we placed it in the former 

 position, denoted hy its most important properties. 

 And here we draw your attention to its affinities to 

 that higher type which we are now about to consider. 



The Class Insecta, to which the House-fly belongs, 

 is one of the most extensive in the Animal Kingdom, 

 and is divided into several Orders, distinguished from 

 each other by well-defined characteristics. The chief 

 typical feature of the whole class is the invariable 

 possession of six legs by the fuUy developed insect 

 {imago), although in the larval stage the number of 

 these members is arbitrary, varying in the different 

 groups; and even in some cases they are entirely 

 absent. Another, although not so constant an attri- 

 bute as the former, is the presence of wings, — mem- 

 bers that are found in no other group of the inverte- 

 brate animals ; and lastly, we may name, as a special 

 but not invariable distinction, the division of the body 

 into three sections (hence the term 'insect^), — head, 

 thorax or chest, and abdomen. 



Vogt, whose classification we adopted in our brief 

 notice of the Class Vermes, divides the Insecta into 

 three great subclasses, characterized by the various 

 degrees of metamorphosis that they undergo before 

 arriving at the perfect state. The forms contained in 

 the lowest of these subclasses {Ametabola) are subject 

 to no important change in their outward appearance, 

 excepting so far as their growth is concerned, from 

 the time of quitting the egg to the attainment of 



