or fry, had been brought by floods or migrating birds, and 

 after a few years become scarce or disappear altogether 

 with the drying up or some other change in the nature of 

 their habitat. 



The Pelecypoda (mussels) are represented by a good 

 number of species and forms, especially in the Tuscarawas 

 river. As the Ohio canal is running in its vicinity almost 

 all along, and connects its waters with those of the Cuya- 

 hoga river, it is of interest to compare their faunas. While 

 the canal is inhabited by no species not found in the river, 

 there are some which present more or less different forms, 

 such as Unio rubiginosus, Margaritana complanata and 

 Anodonta ferussaciana. Of 40 species of Unionidae living 

 in our vicinity, 38 were found in the river, and 14 of these 

 also in the canal. 



In this connection it is of interest to compare the lists of 

 Uuionidpe of the three rivers, Cuj^ahoga, Mahoning and 

 Tuscarawas, as published by Mr. Geo. W. Dean.* As to 

 the latter there are some differences, as will be found by 

 looking over the following list. [Unio perplexus slipped 

 into Mr. Dean's list by a mistake; Unio pustulatus may 

 live in our river further south.] 



Almost all Unionidae are badly eroded, especially on the 

 beaks, so that quite young specimens must be used for the 

 study of the umbonal sculpture. A disease attacking the 

 shells of many Unionidae, especially at the hinges, and 

 badly disfiguring or nearly destroying them, in observed 

 very frequently. The species most commonly and badly 

 affected are Unio lens, circulus, rangianus; Anodonta eden- 

 tula. Microscopic examination has been made in different 

 species, and will be carried further. 



The following list, approximately complete, and notes 

 are the result of ten years' careful collecting and studying. 

 To Mr. Cha.s. T. Simpson, of the U. S. National Museum, 1 

 am indebted for the verification of a number of species, 

 especially Amnieola and Goniobasis; to Prof. B. Shimek, of 

 the lovva State University, for the examination of the 

 Ancyli. 



* The Nautilus, IV, p. 20-22. 



