82 



VICTOR E. SHELFORD. 



4. Influence of Physiography and Vegetation upon Animal Habitats. 



In some cases the evaporating power of the air is apparently 

 largely controlled by the vegetation and in others largely by 

 physiographic conditions while as a rule both physiographic 

 conditions and vegetation play important roles. The impor- 

 tance of the combined effect of physiographic conditions and 

 vegetation is well shown on the steep clay bluffs of Lake Michi- 

 gan. For example, at Glencoe, 111., erosion has rendered the 

 bluff steep and brought the ground water near the surface in 

 some places (Shelford, n 4 ). Forest animals occur among the 

 shrubs and under the dead sweet clover (Fig. 5). 



TABLE IV. 



Showing forest animals in the early stages of forest development of a clay bluff 

 of Lake Michigan. Subterranean and ground strata, i ; bare clay, 2; sweet clover, 

 3; shrubs, goldenrod, etc., 4; sapling stage; animals same as in 5, the oak-hickory 

 forest. 



Common Names. 



Scientific Names. 



Tube weaver 



Lycosid 



Carolina locust 



Mud dauber 



Tiger-beetle larvae 



Sow bugs 



Centipede 



Snail 



Snail 



Snail 



Tiger-beetle larvae 



Snail 



Slug 



Yellow-margined millipede. 

 Centipede 



Aglena ncevia Wai 



Pardosa lapidicina Em 



Dissostiera Carolina Linn 



Pelopaeus cementarius Dru 



Cicindela purpurea limbalis Klg. 



Porcellio rathkei Brandt 



Geophilus sp 



Polygyra thyroides Say 



Pyramidula alternata Say 



Polygyra monodon Rach 



Cicindela sexguttata Fabr 



Polygyra albolabris Say 



Phylomycus carolinensis Bosc. . . 



Fontaria corrugate Wood 



Lyasopetalum lactarium Say. . . . 



X 

 X 

 X 

 X 

 X 

 F 

 X 

 X 

 X 



A 

 X 

 X 

 X 

 X 

 X 

 X 

 X 

 X 

 X 



All of the species beginning with Geophilus are commonly 

 found in the oak-hickory forest. On the covered bluff how- 

 ever, where the moisture content of the soil is great and the 

 dense sweet clover and the shrubs make a good covering we 

 find these animals associated with the earliest stages of vegeta- 

 tion development. Shade and moisture here appear to be the 

 determining factors. We note here then that the forest floor 

 conditions are in advance of the forest while on the dry well- 

 drained sand they lag behind in succession. 



