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 
288 
Fic. 288.—The large green leaf-hopper 
(Draeculacephala mollipes): a, young; 6, one 
half-grown; c, adult; enlarged as indicated 
(after Forbes). 
Fic. 289.—The six-spotted leaf hopper 
(Cicadula sexnotata); enlarged as indicated 
(after Forbes). : 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 
