148 THE AMERICAN MIDLAND NATURALIST 
17. Ortmann, A. E. and Walker, B. “On the Nomenclature of 
Certain North American Najades”. Occas. Papers Museum Zoology, 
University of Michigan, No. 112, July 1922, Ann Arbor. 
18. Walker, B. “The Unione Fauna of the Great Lakes”. Nautilus, 
27. 
*Contribution No. 72 from Biological Laboratory, Washington and 
Jefferson College. 
CORRECTION :—The table of absolute minimum tempera- 
tures of the last issue (Vol. VIII, Nos. 4, 5, July-September, 
1922), gives 17 degrees above zero for January, 1918, and 11 
degrees above for January, 1919. Both of these should read 
“below zero,’ or minus 17 and minus 11. See page 123. 
