TP| USCARAWAS County lies wholly in the coal meas- 



I ures. Rather steep hills, up to several hundred feet 

 high, with horizontal layers, and valleys in all di- 

 rections, are the result of erosion from an ancient high 

 plateau. The main drainage is that of the Tuscarawas 

 river, through the Muskingum, a tributary of the Ohio. In 

 the north a good part of the surface is covered with glacial 

 drift, and more southw^ard the valleys, originally much 

 deeper, are partly filled up with it. Thus the bottom of the 

 river, and of the creeks coming from the north, is coarse 

 gravel and sand, while in those of a southeastern direction 

 it is silt and sand. In spite of all search no remains of 

 mollusca from the glacial epoch have been found in the 

 gravel bed so far. 



New Philadelphia, in about the centre of the county, is 

 at pbout 930 feet above sea level, and 330 feet above the 

 level of Lake Erie. 



The original woods are cleared away more and more 

 ever^^ year; this is not only injurious to the climate, but, 

 what is of special interest in connection with our subject, 

 destructive to molluscan life. Severe winters with little 

 protection from snow, prolonged dry " spells " in summer are 

 the consequences, and the small and smaller parcels of for- 

 est remaining are unable to retain the humidity of soil and 

 air necessary for our land mollusca. Thus certain species 

 have become quite rare, and some of thetn may even be ex- 

 tinguished in a near future in many sections. Thus e. g. 

 Zon. multidentatus Binn. has been collected sparingly at 

 Goshen, on the steep slope above the canal, prior to 188(3; 

 but since then no specimens could be found. 



For fresh water gastropoda the conditions are not very 

 favorable, as there are no lakes nor extensive swamps; yet 

 a good number of species have been found. They are sub- 

 ject to many changes, as also in other parts of the country. 

 A species may occur, and even abound, Id a certain locality, 

 a pool, or ditch, where specimens, respectively their young, 



