Page:Popular Science Monthly Volume 70.djvu/63

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Tabular Summary of the Development of Insects in the Various Geological Periods


PSM V70 D063 Summary of insect development in various geological periods.png


The signs +, —, = denote that, compared with the same group as now existing, a group falling in a given period was relatively more abundant, smaller, or equally developed, respectively, in the next younger period.