26 SAND DUNE REGION OF SAGINAW BAY. 



Mud Creek, located in Caseville Township and emptying into Wild 

 Fowl Bay just west of the base of Sand Point, is the only stream in the 

 region studied that does not head in the "hill district." It is nothing 

 more than a small creek that flows for most of its length through the 

 clay country, and is very sluggish in the sand region. It was only 

 studied near its mouth where the following species of fish were taken: 

 Lepisosteus osseous, Ameiurus vulgaris, A. melas, Pimephales notatus, 

 Semotilus atromaculatus, Notropis cayuga, Umhra lima, Amhloplites 

 rupestris, Micropterus salmoides, Perca flavescens. 



Saginaw Bay: About Sand Point and all along the coast to the east 

 the bottom of Saginaw Bay is sand, except at Oak and Hat Points. 

 (Plate I a.) This sand is practically devoid of pebbles and forms a clean 

 hard bottom out to considerable depths. Except for the fish, the 

 biota of the margin of the httoral zone only was studied. The shallow 

 water part of this zone is nearly everywhere devoid of vegetation, owing 

 to the shifting nature of the substratum and the action of the surf. 

 The animal life is also very meager for the same reasons. The fish 

 taken in this habitat are: common sucker, spawn-eater, red-fin dace, 

 red-fronted minnow, trout-perch, rock bass, wall-eyed pike, perch, 

 log perch, black-sided darter, spindle darter and miller's thumb (one 

 specimen). No bottom forms were found until the deep littoral zone 

 was reached. For the mollusks of the deeper part of this zone see Baker. 



The north shore of Stony Island is rocky (Plate XIV) ; at Oak Point 

 there are large rocks off shore, and at Hat Point the bed rock forms 

 a cliff and a small high island off shore. The rocks at these points are 

 covered with a coating of algae and in the crevices there may be a 

 scattered growth of the rush, Scirpus atnericanus. Here, as pointed 

 out by Baker, are to be found the univalve mollusks with large feet — 

 Physa, ancillaria tnagnalacustris, Lymnaea emarginata ontarioensis 

 and Goniohasis livescens. Leeches were also found here. 



Where the bars are being elevated above the water, e. g., on the west 

 side of Oak Point, the end of Sand Point and the south side of the 

 base of Sand Point, shallow bays are being formed. Those in the first 

 two places mentioned are shallow and floored with sand both for the 

 reason that the drift is great along this shore and much sand is washed 

 into them before they become separated from the bay and also because 

 a large amount of sand is blown into them after the barrier beach has 

 been raised above the surface of the water. In general it may be said 

 that the substratum of sand here, as on the beach, is an unfavorable 

 factor, and the elimination of the wave action a favorable condition, 

 the two partially offsetting each other. Thus the vegetation is sparse 

 (mostly sedges) but better represented than off the exposed beaches. 

 Even before the barrier beach has been elevated above water its in- 



