SAND DUNE REGION OF SAGINAW BAY. 27 



fiuence in checking the force of the waves is shown by a narrower 

 lower beach and the presence of a Httoral zone of sedges, as at the 

 end of Sand Point. That the fauna also responds to these conditions 

 is shown b\' the abundance of clams (see Baker) on and between the 

 bars and in the lagoons, and a muskrat house on the bar at the end of 

 Sand Point. 



The bay (Turtle Bay) on the south shore of Sand Point differs from 

 those just mentioned in being itself at the head of a bay (Wild Fowl 

 Bay) and thus protected from severe wave action. (Plate VII b, 

 XlII b.) The beach of the sand spit that is enclosing this body of water 

 is narrow, and the marginal rushes and sedges are rather well repre- 

 sented. In the bay itself there is a deposit of mud and a rich aquatic 

 flora and fauna. The animals found here are: snapping turtle 

 (abundant), painted turtle, Blanding turtle, dog-fish, gar pike, long- 

 jawed catfish, bullhead, Mississippi catfish, mullet, golden shiner, 

 grass pike, calico bass, rock bass, sun fish, large-mouthed black bass, 

 perch, log perch, Iowa darter, spindle darter, wood duck, black duck, 

 and other more or less aquatic birds. 



THE GEOGRAPHIC RELATIONS OF THE TERRESTRIAL FLORA AND 

 VERTEBRATE FAUNA OF THE SAND DUNE REGION. 



As previously stated, the main reason for selecting this region for 

 study was to determine, if possible, the effect upon the biota of the 

 slightly more equable climate that this coast is supposed to have. 

 It has become evident upon a study of the material and the literature 

 that this question cannot be definitely answered as yet, owing princi- 

 pally to our lack of knowledge of the biota of other parts of the state. 

 For this reason it has been made the first aim of this report to present 

 the conditions in the region studied so that the data may be available 

 for future comparison when more work has been done in the interior 

 of the state. There are, however, a few conclusions concerning the 

 geographic distribution of some of the forms in the region that seem to 

 be warranted. 



Before taking up the discussion of the affinities of the terrestrial 

 fauna of the sand region the general geographic conditions in southern 

 Michigan should be briefly outlined. In the first place, there are no 

 physiographic barriers to migration, as there are no high elevations, 

 large streams, etc., so that as far as this factor is concerned there seems 

 to be no reason why any form cannot range over practically the entire 

 area if favorable habitats can be found. This peninsula, however, 

 extends through four degrees of latitude, and furthermore, as is well 



