LOW PRAIRIE 



283 



on the ground. The 6-spotted spider (Dolomedes sexpunctatus) preys 

 upon the other small animals. The common toad and the marsh tree- 

 frog (Chorophilus nigritus) are common (139). The latter is particularly 

 abundant in the autumn. Its eggs are laid in April in the temporary 

 pools. Transformations are complete by the last of May. The prairie 

 garter-snake {Thamnophis radix) was formerly common. It is known to 

 feed upon the swamp tree-toad. The prairie water-snake (Tropidonotus 

 grahamii) was formerly common in and about prairie sloughs (22). 



The bobolink builds a nest here in a bunch of grass; the meadow 

 lark and dickcissel build nests of grass and weeds, usually arched over. 

 The bisons, residents of the high prairie, were fond of rolling in the low 



r 



288 



Fig. 288. — The large green leaf-hopper 

 (Draeculacephala mollipes) : a, young; b, one 

 half -grown; c, adult; enlarged as indicated 

 (after Forbes). 



Fig. 289. — The six-spotted leaf hopper 

 (Cicadida sexnotata); enlarged as indicated 

 (after Forbes). 



iM*F 



|# 



w. 



289 



wet places on the prairie and covering themselves completely with mud. 

 This must have destroyed numbers of pond animals and badly disturbed 

 others. 



b) The field stratum (Stations 42, 43, 44, 45; Table LXVI). — This 

 is the chief stratum. While various conditions of the subterranean 

 and ground strata, depending upon nearness to ground water, could be 

 recognized, our studies have not been sufficiently detailed to warrant 

 attempts at separation. A girdle of bulrushes can, however, often be 

 distinguished. 



Bulrush girdle : Two of the large green leaf-hoppers {Draeculo- 

 cephala mollipes [Fig. 288] and Cicadula 6-notata [Fig. 289]) are common. 

 The damsel-bug (Reduviolus ferus), which feeds upon leaf-hoppers, is 



