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POPULAR SCIENCE REVIEW. 
character of the single wing thus named is doubted by Mr. 
S. Scudder in his work on fossil butterflies. Two other supposed 
secondary butterflies have been criticized by the latter author, 
one of which specimens he has personally examined and declared to 
belong to another order ; and the other, which he has not seen, 
he does not think is lepidopterous. This examination leaves 
Lubbock’s generalization true, for the present, that the Lepido- 
ptera only appear in Tertiary strata. We see no reason, however, 
why they should not have appeared earlier, say at the beginning 
of the Cretaceous epoch, when true flower-bearing plants first 
made their appearance, although the first flowers may have 
blossomed more for Hymenoptera than Lepidoptera ; and, 
indeed, the fact that the first flowers were polypetalous rather 
than gamopetalous — that is, had corollas made up of separate 
petals, rather than of the petals all joined together as we 
find them in the common blue-bell ( Campanula ) — is an indi- 
cation that gamopetalous flowers could only be formed when 
there were insects with proboscides long enough to be thrust down 
to the nectaries at their bases, as we find them in butterflies 
and moths. 
Thus we see there is a broad parallelism between the 
appearance of the more differentiated types of the vegetable 
kingdom, and the development or appearance of various orders of 
insects. Instead of the appearance of a new order, the differ- 
entiation may have been accompanied by such specialization of 
a large group as the bees among Hymenoptera. Mr. H. Gross 
has published three very important papers on the insect fauna 
of the primary, secondary, and tertiary periods, in which he has 
given the proportion of species. Of these we observe the Cole- 
optera or beetles are best represented. It is one of the most 
extensive in its geographical distribution — a fact which always 
indicates the antiquity of organic forms, as it proves they were 
spread before those physical geographical changes occurred 
which give the surface of the earth its present features. 
Among the beetles, also, we find a very extended differentiation ; 
their genera are adapted to almost every habit of life, aquatic, 
subterranean, and terrestrial. They are aborted as well as 
developed, as in the case of the glow-worm. They live on 
carrion, fungi, pollen, nectar, wood, leaves, and other organic 
substances, and have their structures modified accordingly. 
Hence we cannot be surprised that the Coleoptera seem to have 
been from the first a dominant order, seeing how useful beetles 
have made themselves in the economy of the globe. Perhaps also 
the durability of their hard wing-cases ( elytra ) has frequently 
enabled them to be fossilized when other insects would have 
been decomposed, and thus caused them to appear numerically 
more abundant than contemporary orders. 
