Insects of Past Ages. 



8i 



forms of these Insects have been discovered. 

 Some remarkable forms of book-Hce ^ have been 

 found l^reserved in amber. In one of these- 

 the wings are developed and carried so that 

 they resemble the wing-covers of a beetle. 

 Another,^ which has near relations still living 

 in Ceylon, is covered with scales like those of 

 butterflies. 



Reference has been briefl\' made to the 

 occurrence of Insects like may-flies in the 

 carboniferous period. They began to appear 

 in the Devonian period, which is older than the 

 carboniferous, but in the rocks of the latter 

 period they are represented by so many species 

 that Sc udder has been led to remark that our 

 existing species appear to be only the lingering 

 fragments of an expiring group. The marvel 

 is that Insects of so fragile a character should 

 have been preserved as fossils. 



The caddis-flies are supposed to date from 

 the secondary epoch on the evidence of some 

 wings found in the lower beds of the Purbeck 

 limestone ; and a larval tube has been found 

 in the chalk of Bohemia. In the tertiary rocks 

 their remains are plentiful. They arc common 

 in amber, and it is remarkable that a case has 

 been found in this preservative. This implies 

 that in tertiary times some of the species were 

 land Insects in their larval stage. Scudder 

 found them exceedingh' abundant in the 

 tertiary lake basin at Colorado ; and at 

 Auvergne there are beds known as indusial 

 limestone, two or thrt'c vards thick, which 

 consist mainly of caddis-cases. Ants appear 

 to have been the most abundant of all Insects 

 in tertiary times. They are i-ommon among 

 the Insects found in amber, which is of the 

 miocene age. Beetles have been found in the 

 secondary rocks ; also flies as early as the lias. 

 The bugs are more ancient, and fossils obtained 

 from the Permian series of the pal?eozoic epoch 

 are supposed to represent both the two sub- 

 orders, and other representati\-es have been 

 obtained from the (-arboniferous shales of Commentry 

 found in a fossil state in tertiar\' rocks. 



Inskcts in 



Thr two upper Insects are ants ; the other is'not very 

 distantly related. .AH these Ins<-cts were caneht by thi? 

 sticky resin (lowing (roin pine tribes in the niioceiie age, 

 which afterwards t!ecanie fossilizefl into atiilxT. The 

 middle example is magnified forty times : the others 

 twenty -five times. 



Wasps and thrips have been 



' Psocida> 



- Sphitrojisocus kunowii. 



Amphientomum paradoxum. 



