78 



Marvels of Insect Life, 



alwa3/s forming the rocks of the future. Insects, though exceedingly numerous, 

 dwell mostly on dry land, and their bodies are so fragile that they are 

 not calculated to stand the rough and tumble of such a process ; so that 

 we may conclude that the fossil Insects that have been found can give us only 

 a very imperfect idea of a few of the multitudinous forms that of old prevailed 

 on the earth. But although this imperfect record will not enable us to trace the 

 evolutionary progress of the race of Insects, it is yet full of interest as showing the 

 antiquity of certain types. The earliest forms of Insects we may presume were as 

 delicate as our modern spring-tails and bristle-tails, which have no hard parts, and 

 so were little likely to leave fossilized remains. It has been claimed that certain 

 remains found in rocks so ancient as the silurian are those of primitive Insects, 

 but this view is contested by some of the best authorities. 



The earliest known undoubted Insects are found in the carboniferous rocks, 

 which are of great antiquity and classed by geologists among the primary, or palaeozoic, 



rocks. This was the age 

 of the coal-formation, and 

 } .. from these rocks, both in 



Europe and in North 

 America, numerous fossil 

 Insects have been 

 obtained. These carbo- 

 niferous Insects come 

 close to our modern cock- 

 roaches in structure. 

 They had four wings of 

 similar size and shape, 

 but all transparent, like 

 the four wings of a ter- 



Photo h\ 



rir. Tivs/. 



Head of Earwig. 



The fore-parts of tlif common earwig are here shown on a scale of twelve times the actual 

 size to illustrate the character of the mouth organs, which are admirably adapted for cutting. 



mite. In the modern 

 cockroach, it will be re- 

 membered, the first pair 

 of wings are thickened and opaque. In the carboniferous cockroach not only are all 

 the wings similarly transparent, but they also agree in having five nervures. Now, in 

 the modern cockroach, though the hind-wings have five nervures, those of the fore- 

 wings have been reduced to four. So here we have evidence of two modifications 

 in cockroach wings. We see something of this modification in the trias and lias 

 of the secondary, or mesozoic, epoch, where the fossils of cockroach-like Insects 

 have wings intermediate in character between those of the carboniferous and those 

 of the present day. 



Ihe fossils of the carboniferous period appear to point to the fact that the 

 order 1 to which the cockroaches belong is certainly among the most ancient of 

 Insects with firm structures ; for it includes among its families the stick-Insects 

 and the grasshoppers, and both of these families had their representatives at this 

 remote period. Others, still with equal wings, exhibit a tendency towards the 

 structure of the modern may-flies and dragon-flies. It is remarkable that only the 



^ Orthoptera. 



