Occasional Papers of the Museum of Zoology 5 



inflow for years. The molliisks are those of a stagnant pond, 

 Aplexa and, Segmentina thriving here as weh as in the Lac 

 aux Morts complex to the north. The similarity of the two 

 faunas bears out the geological evidence of a former connec- 

 tion between Lac aux Morts and the ^Nlauvaise Coulee. The 

 bottom of the coulee is gravelly, covered with a soft muck of 

 varving depths, and cat-tails and rushes are abundant on the 

 shores. Above the coulee on old shore lines are woods of the 

 usual type, favorable to the smaller land shells. 



Lac aux [Nlorts : A shallow lake of irregular outline, lying 

 north of Devils Lake. Live snails in quantity were taken 

 from marshes north of the lak^ and at one time undoubtedly 

 a part of it. 



Sweetwater Lake : The largest of the chain of lakes. It 

 has a gravelly bottom and reeds and rushes along its edges. 

 The water is slightly alkaline. It is probable that further 

 collecting will add several species to the list from this lake. 



Stump Lake : This is of the same character as Devils Lake, 

 decidedly alkaline and devoid of mollusks. A small fresh pond 

 at the south end of the lake, near a spring, was a suitable hab- 

 itat for two species of snails. Lyuuuca palustris and Planor- 

 bis pan us. 



Sheyenne River : Collections were made at several points 

 south of Devils Lake, where the stream is narrow and lies in 

 the old valley, wide and deep with steep sides. The current 

 is swift, and deep holes alternate with rocky rapids and shal- 

 low sand-bars. Sphaeriuiii declive lives on the bars, and clams 

 inhabit the deeper places in soft bottom. The only live An- 

 cylidae taken were found on stones and clam shells in this 

 river. 



Wood Lake: A small fresh lake near the Sheyenne River, 

 similar in many respects to Court Lake but with a sandy hot- 



