VOL, VIII. NOVEMBER, 1922 NO. 6 
witty MIDLAND 
NATURALIST 
Devoted to Natural History, Primarily 
that of the Prairie States 
Published by the University of Notre Dafne) 
Notre Dame, Indiana 
J. A. NIEUWLAND, C.S.C., Ph. D., Sc.\D., Editoi 
CONTENTS 
Observation on the Rate of Growth of the Shell of Lake 
Dwelling Fresh Water Mussels N. M. Grier, Ph. D. 129 
Euglena Viridis (Ehrenberg) Sister M. Ellen 149 
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