ON CLAY 213 
a) Subterranean-ground stratum.—Perhaps the most characteristic 
animal of the steep bluff is the bluff tiger-beetle (55, 151) (Cicindela 
purpurea limbalis) (Figs. 159-67). In the open places of this stage, the 
larvae, which live in curved cylindrical burrows (Figs. 165, 166), are 
common. 
The female beetle is provided with an ovipositor (Fig. 159) adapted 
to making small holes in the clay in which eggs are laid (Figs. 160, 161). 
CLay-BANK INHABITANTS 
Fic. 166.—View of larval burrow of the tiger-beetle; natural size. 
Fic. 167.—The adult tiger-beetle (Cicindela limbalis); about twice natural size. 
Fic. 168.—The clay-bank spider (Pardosa lapidicina). 
Fic. 169.—A snail of the shrub stage (Polygyra monodon); enlarged. 
Fic. 170.—The snail (Polygyra thyroides); enlarged. 
The larva (Figs. 162, 163) on hatching from the egg digs a burrow in the 
position of the ovipositor hole. The eggs, which are laid in June, hatch 
in two weeks and the larvae live in the spot where the eggs were laid 
for one year, and transform into pupae (Fig. 164) in the ground in an 
especially prepared cavity (Fig. 165). The adult, which is a reddish- 
