THEIR RELATION TO EACH OTHER 87 



only in the fact that the wings have numerous longi- 

 tudinal and transverse veins, breaking them up into 

 many small areas so as to appear more or less netted. 

 But in the detailing of habits and suggesting lines of 

 descent, further subdivision is convenient. 



Thus the Ephemerida or May-flies contain neither 

 parasitic nor predatory forms. In the larval or early 

 stages they live in the muddy bottom of streams, feed 

 on the organic life contained in this material and, in 

 the adult stage, do not feed at all. Yet it is here that 

 the highest orders get their start and in them predatory 

 and parasitic types are numerous. 



In the Plecoptera or stone-flies we have a similar 

 record except that the mouth structures in all stages 

 are much better developed. Here the larval stages 

 are passed under submerged stones, usually in running 

 streams, and the food consists of such floating organic 

 material as is carried in. The adults in s/pite of their 

 rather well-developed mouth organs have not been 

 observed feeding. 



The Mallophaga or biting lice are animal parasites 

 and are dealt with in Chapter VII, and the Corrodentia 

 or book- and bark-lice are feeders on dry or dead or- 

 ganic matter; not really scavengers, but nevertheless 

 removers of dead material. 



The order Isoptera, containing the Termites or 

 white ants, is interesting from its communal life and 

 will be referred to again; but it depends entirely upon 

 vegetable matter for its subsistence and mainly upon 

 dead tissue. 



The order Platyptera is the first of the Neuropterous 

 types to contain predatory forms and, while it is aquatic 

 like the Plecoptera, has the metamorphosis complete and 

 is altogether much better developed, albeit the adults 

 are loose- join ted and flabby enough, when handled. 



