162 
Psyche 
[June 
would come naturally according to his palaeontological evi- 
dence, the arrangement would have been the same as that 
proposed by me. Tillyard, who has most recently proposed 
an arrangement, differs from my proposal only in the 
relative position of Hymenoptera and Diptera, which was 
based on newly discovered ancient fossils which he identi- 
fied as hymenopterous, perhaps erroneously. Whether he 
is right or not, there is abundant evidence in the complete- 
ness of the differentiation of the families of Diptera in 
Tertiary times to establish its seniority to the Hymenop- 
tera. The same kind of evidence makes Lepidoptera the 
youngest of all. 
The chronological order permits the expression of all 
the accepted genetic relationships with the lower group 
as acceptably as any other, and is the only basis for the 
arrangement of the major orders, the adoption of which 
would result in uniformity. This order is 
Orthoptera 
Hemiptera 
Coleoptera 
Diptera 
Hymenoptera 
Lepidoptera 
