TABLE OF CONTENTS. 
PAGE 
A summer resting stage in the development of Cyclops bi- 
cuspidatus Claus, . . E. A. Birge and C. Juday, 1 
Some aquatic invertebrates that live under anaerobic con¬ 
ditions, .... Chancey Juday, 10 
Dissolved oxygen as a factor in the distribution of fishes, 
Chancey Juday and George Wagner, 17 
Notes on the fish fauna of Lake Pepin, . George Wagner, 23 
Anatomical and histological studies of the digestive canal 
of Cirnbex americana Leach (with Plates I-IV), . 
Henry H. P. Severin and Harry C. M. Severin, 38 
Habits of the American saw-fly, Chub ex americana Leach, 
with observations on its egg-parasite, Trichogramma 
prStiosa Riley (with Plate V), 
Henry H. P. Severin and Harry C. M. Severin, 61 
Description of a new subterranean Amphipod from ’Wis¬ 
consin (with Plates VI and VII), . S. J. Holmes , 77 
Concerning the organization of the spore mother-cells of 
Marsilia quadrifolia (with Plates VIII and IX), 
W. Marquette, 81 
