58 POPULAR SCIENCE MONTHLY 



Although in comparison with the hosts of living forms, researches 

 hitherto made have resulted in the insignificantly small number of 

 about 10,000 species of fossil insects, yet these few afford us a glimpse 

 into the insect life of past ages. Such a collection of extinct species, 

 moreover, much exceeds in numbers the recent forms in most univer- 

 sity and private collections, which have become the basis of so many 

 bold hypotheses. We can thus see or at least have some idea how in 

 the course of millions of years the present mighty tree has grown up 

 from so small and tender a plant. 



Of the fossil insects thus far obtained, the larger part have come 

 from that important period immediately preceding the age of man. 

 This is designated the Tertiary period, or the age of mammals. Those 

 insect remains preserved in fossil gum (Baltic amber), like artistic 

 and permanent microscopic preparations, are indeed well known, and 

 of these many thousand specimens have been accumulated in museums. 

 On the other hand, less noted, but not less numerous, are the wonder- 

 ful impressions found in many places in laminated shales, as in 

 OEningen (Baden), Kadoboj (Croatia), in Italy, on the Ehine, in 

 Provence, in North America, etc. These are to be likened to nature's 

 own printing and provide us with an atlas of the Tertiary fauna in 

 which we find very many species that can scarcely be distinguished 

 from those living to-day. With the exception of bird-lice, lice and 

 fleas, all the principal existing groups of insect throngs are represented 

 in Tertiary time, but the remarkable bizarre forms which especially 

 delight our eyes to-day were much fewer in number then than now. 

 Thus very few large butterflies and no striking types of beetles, such 

 as we are accustomed to see in all shop-windows of the dealers, have 

 been discovered. 



Even though the character of the Tertiary fauna in general did 

 not vary essentially from that now in existence, still the distribution 

 of forms over the earth must have been far different. For instance, in 

 Germany we find elements that now are met with only in tropical 

 lands, from which follows many a conclusion as to the variations of 

 climate and of the plant world. Moreover, the numerical distribution 

 of species in kindred groups was likewise not the same as that at 

 present in force, since among the Tertiary Hymenoptera a much 

 smaller percentage of bees is found, among the Diptera there are more 

 gnats than flies, among the Orthoptera far more grasshoppers than 

 locusts, and only very few walking-sticks, etc. 



Further, when it is stated that in the Tertiary period no single 

 type of insect has been hitherto identified which does not still exist, 

 and that therefore the numerous amber preparations and the impres- 

 sions so beautifully preserved are as yet capable of giving no direct 

 answer to our question, we must then turn to the next older period, 



