»909.] FRESH-WATER FAUNA IN PENNSYLVANIA. 91 



ments " connected with it, the fresh-water fauna has deteriorated, 

 has become poor, and in many cases extinct. Yet it is not reaHzed 

 how far this process has advanced, and to what extent the fresh 

 water of this region has become unfit for the indigenous hfe. The 

 present paper has the object to record the present state of things in 

 this respect, and to point out which rivers and creeks are in such a 

 state that they do not offer any more the required conditions for 

 animal life, and which are yet in a good or fair condition. It may 

 be remarked that all facts collected here have been ascertained by 

 the writer in person, in the course of his studies during the last five 

 years. All streams recorded on the map accompanying this paper 

 (Plate VI) have been visited by the writer, and collections of their 

 mvertebrate fauna and observations on their vertebrate fauna have 

 been made, wherever such was still present: but in many cases his 

 efforts were in vain, and life had entirely disappeared in many 

 streams. The blue color on our map tells a pitiful story, pitiful not 

 only from the standpoint of the scientific man, but also with refer- 

 ence to the question of utility. For we must not forget that the 

 original fauna of the fresh water forms part of the " natural re- 

 sources " of the country. In many cases the direct economic value, 

 chiefly of the fresh-water invertebrates, is not very apparent; but 

 considering the fact that all forms of life in an ecological com- 

 munity are mutually dependent upon each other, we realize that the 

 more important forms (mussels, fishes and aquatic mammals) can- 

 not be preserved, unless the creatures which furnish the necessary 

 conditions for their subsistence are also preserved. Thus the de- 

 struction of our fresh-water fauna forms a chapter of the book on 

 the destruction of our natural resources, a record which is not at 

 all to the credit of the nation. 



I. The Fresh-Water Fauna. 



The part of the fresh-water fauna which has chiefly been studied 

 by the writer is, as has been stated, the invertebrates. However, 

 during his investigations, he kept his eyes open for vertebrate life, 

 and among the latter it is chiefly the fishes to which he paid atten- 

 tion. He did not make systematic collections of the fishes, and thus 



