146 University of California Puhlications. [Entomology 



cross veins are, as a rule, so diverse that only in allied groups 

 can comparisons be made with any confidence. 



The relationship between the groups is more clearly shown 

 by the wings than by any other set of characters. There are 

 a number of cases of parallel development, producing groups 

 that are convenient, though not natural. The Suhulicornes 

 have two entirely distinct venations, showing the two groups 

 not to be really closely allied, but should have been brought 

 closer together than in the accompanying diagram (Fig. 101). 

 The groups of the Corrodentia are probably not as distinct as 

 indicated on the diagram and possibly should be derived from 

 the same line as the Orthoptera, notwithstanding the absence 

 of ancient fossil remains. The Elytroptera certainly consist 

 of independent groups. The Neoptera are all closely allied to 

 each other, but here, also, the group is probably not mono- 

 genetic. While the diagram here given is based on the 

 venation, it is nowhere contrary to evidence obtainable from 

 the study of other characters, and, modified in the manner 

 just indicated, represents the author's views of the phylogeny 

 of the groups of insects. The sequence of the orders should be 

 as follows: 



1. Aptera. 



2. Neuroptera. 



3. Odonata. 



4. Ephemerida. 



5. Corrodentia. 



6. Orthoptera. 



7. Hemiptera. 



8. Coleoptera. 



9. Diptera. 



10. Hymenoptera. 



11. Lepidoptera. 



