PRESIDENT'S ADDRESS, 339 



respiratory structures — these in same instances resembling in 

 some degree the primitive form but not occupying position pre- 

 viously pre-empted b}'' wings. 



The bearing oi these conclusions on the early phylogeriy of 

 the gToup of insects is evident and we are practically forced to 

 carry the origin of the group back more remotely in time to connect 

 it as seems necessary with a primitive, wingless, tracheate ancestor. 

 The elaboration of snch a phylogeny in so far as the evidence may 

 justify is beyond the scope of this address but its general bearing 

 may be indicated in graphic form by adaptation of the diagram 

 showing the distribution of different groups of insects in time. 

 The diagram adapted from latest edition and translations of Zittel's 

 Paleontology is of course poorly adapted to show tlie i^resent views 

 of direct affinity but will serve oiir purpose to indicate time of 

 appearance of different orders. 





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