ON SOME OF THE FOSSIL TETTIGIDJE. 177 



these insects undergo an incomplete metamorphosis 

 and are more or less active in their pupal conditions, 

 that they are better suited to countries and districts 

 where they are not siibjected to the rigours of a long 

 and cold winter. 



(Eningen is situated to the north-west of Constance, 

 on a narrow arm of the lake which discharges itself 

 into the Rhine. The insect-beds occur in two quarries, 

 which were the floors of former ancient lakes. In the 

 lower quarry an extremely fine grey limestone occurs, 

 which, although only one inch thick, may be split 

 into 150 layers as thin as paper. These layers contain 

 numerous sharp impressions of insects. Although so 

 thin, the layers probably required a long series of 

 years for their deposition, during which time the 

 insects mixed with numerous plant remains were stored. 

 Amidst this flora are to be found male flowers of the 

 poplar and those of the camphor-tree, which last plant 

 requires a warm climate to perfect them. Fruits of 

 Diospyros (the date-palm), seeds of elm, and of the 

 willow-tree also occur. Such a climate as is required 

 by the camphor-tree of Japan and China, the fan-palm, 

 and the elegant tree-fern, suited well the economy of 

 gigantic insects like Cicada emathion, which then chirped 

 to their mates in the foliage, just as recent Cicadge do 

 now in the semitropical heats and mild climates of 

 Madeira and N. Africa. 



Volcanic action was rife in many places during 

 those Miocene days, and possibly noxious gases and 

 acid vapours passing over large districts slew millions 

 of insects, which, falling on the rivers and brooks, 

 finally found rest in still water and its mud. 



A highly interesting chapter on the probable climate 

 of the Swiss Miocene will be found in Dallas's trans- 

 lation of Heer's ' Primaeval World,' vol. ii. p. 126. 



The Quaternary series of beds is singularly barren 

 of insect remains. Probably the drifts and gravels 

 were ill suited to preserve the insects which visited 

 the flowers and fruits of this later period. A few 



VOL. II. N 



