PIONEER COMMUNITIES I41 
formation because of their breeding relations. The large-mouthed 
black bass, the bluegill, the pumpkin-seed, and the speckled bullhead 
all make nests on the sand, the male fish guarding the nests and driving 
off other fish that approach. These species are the same as those of the 
bare-bottom formations of a lake. In their feeding the fish belong in 
part to another formation in the pond, namely, that of the chara. 
Character of the formation: The formation may be designated as the 
bare-bottom formation, the forms present being those that are dependent 
Fic. 85.—Shows Pond 1 at the extreme low water of the drought of t908. In the 
spring the old boat is usually covered with water. In the foreground a large area of 
bare sand bottom is shown; to the right a few rushes and sedges. The absence of 
shrubs near the water’s edge should be noted. 
upon bare bottom in their most important activities—the fish in breeding, 
the caddis-worms in making their cases, the mussels in their general 
activities. It is necessary for the mussels to be on bare bottom_in order 
to maintain themselves in an upright position. 
Tendencies in the formation: This formation is similar to that of the 
bare bottom of lakes. The vegetation comes in, as has been indicated in 
the protected situations, and the bare bottom disappears, its place being 
taken by the chara. The chara gives rise to humus, upon which chara 
