16 PAPERS OX ZOOLOGY OP MICHIGAN. 



Sparganium sp? — Often formed a thick growth in shallow water. 



Ericaulon articulatum (Huds). — A rather conspicuous growth in 

 places where there were but a few inches of water. 



Lobelia Dortmanna L. — Found growing with the Ericaulon. 



Potomogeton. — Several species grew on the shoal, principally on the 

 outer part. 



Brasenia jjurpurea Casp. — Patches were often present on deeper 

 shoals. 



Haliitat Distribution of Fish in South Twin Lake. 



Station 1. This is the shoal and adjacent shore at the extreme 

 north end of the lake. The shallow water area is comparatively ex- 

 tensive with a bottom of hard sand. Over this is a scant growth of 

 rushes, which form the only conspicuous vegetation. The shore zones 

 of plants are distinct, but the low bush or heath zone practically covers 

 the beach (Plate II). 



Fishing with the hand seine was done on the morning of August 28 

 in water that was mostly between one and two feet in depth. The 

 water temperature was 70° F. Fish were few and were not moving on 

 the shoal: those taken were found resting beneath objects such as 

 overhanging bushes, an old row boat and pieces of water-logged bark. 

 The following species were collected: 



Rhinichthys atronasus lunatus. — Several taken. 



Semotilus atromaculatus.- — Several small specimens taken. 



Microptenis sahnoides. — One small specimen 4.2 cm. long was caught. 



Station 3. This is a shoal which differs from that of Station 1 in 

 being much narrower, a depth of three feet being reached about thirty 

 or forty feet out from the shore. The shore features are similar to 

 those of Station 1, and this is also true of the bottom which is composed 

 of a similar hard, reddish sand with little vegetation (a few rushes and 

 other plants). Many logs (Plate III) were floating near the shore. 

 Collecting w^as done with the six-foot minnow seine in water three feet 

 or more in depth and there was no difficulty in getting a representative 

 collection of fishes for they showed little fear of the net. 



The invertebrates found were : 



Macrohdella decora. — This large leech was common. 



Dragon-fly nymphs and eggs of Tetragoneiiria sp. — The latter were 

 in long strings of jelly-like substance. 



Caddice worms. 



The fish taken were : 



Semotilus atromaculatus. — Small specimens found in water less than a 

 foot deep. 



