The Larva Habits of Fresh-water Mussels 287 



with branched hairs. These are erect forked hairs ad- 

 jacent to the rim, and flat-topped four-rayed hairs over 

 the remainder of the wall space. These hairs project 

 into the dissolved fluids, as do roots into the nutriet 

 solutions in the soil, and their function is doubtless the 

 absorption of food. 



II 



The larval habits of fresh-water mussels The early life 

 of our commonest fresh-water mussels is filled with 



FIG. 175. Small minnows bearing larval 

 mussels (glochidia) on their fins. 



shifts for a living that illustrate in a remarkable way 

 the interdependence of organisms. The adult mussels 

 burrow shallowly through the mud, sand and gravel of 

 the bottom (as noted on page 108) or lie in the shelter of 

 stones. Their eggs are very numerous, and hatch into 

 minute and very helpless larvae. For them the vicissi- 

 tudes of life on the bottom are very great. The chief 

 peril is perhaps that of being buried alive and smoth- 

 ered in the mud. In avoidance of this and as means 



