PLATYFTERA. 99 



in such groups. Paiasites living upon other animals, 

 and subsisting upon the food provided by the host, 

 are usually wingless, and are generally looked upon as 

 having been evolved from more normal winged forms. 

 They are examples of speciahzation through reduction 

 of parts, and usually have lost the wings, and often 

 the biting mouth parts, etc., probably because of dis- 

 use, or some cause directly connected -with their 

 peculiar mode of hfe. We repeat that they should 

 be placed, therefore, after the normal forms of the 

 types to which they are allied, and not before them, 

 as is very often done in text-books. Among the 

 Platyptera the Termites are considered by Dr. Hagen, 

 the most thorough student of these singular forms, to 

 be allied to the Orthoptera, and Brauer considers 

 them to be similar, also, to the Dermaptera. 



