OF CONCHOLOGY. 241 



REMARKS ON SOME OF THE MOLLUSCA OP THE VALLEY 

 OF THE MOHAWK. 



BY JAS. LEWIS, M. D. 



Since 1853 the opportunities the writer has enjoyed for study- 

 ing the molluscs found in the Valley of the Mohawk, have 

 brought to notice a few species regarding which a few interesting 

 facts may be mentioned, some of which may not be without im- 

 portance, inasmuch as they show in what manner species not 

 heretofore indigenous become colonized and acclimated. There 

 are no positive facts going to show that other species than those 

 which are about to receive attention have recently been intro- 

 duced in the Mohawk Valley, but the characters of a few species 

 which were abundant as early as 1853 are such as to suggest 

 that they may possibly have been introduced, as others have 

 since that date, through the waters of the Erie Canal. 



The first species that presents itself as recently introduced is 

 Melantho (Pal.) rufa, Hald. Those which were first observed 

 of this species were found in the canal at Mohawk, N. Y., about 

 1856-58. The specimens were small but well characterized, 

 and might be regarded as having attained a growth of from two 

 to three years. Each successive year has presented to notice 

 specimens of gradually increasing size, until in 1868 specimens 

 were found nearly or quite If inches long. A year or two after 

 this species was noticed in the canal a few specimens were found 

 in the Mohawk River at Utica. Later they were detected in 

 the river near Mohawk, where now they are apparently estab- 

 lished, but do not form a very conspicuous portion of the class 

 they represent, being greatly exceeded in numbers by 31. decisa, 

 which appears to have been the sole representative of its genus in 

 the river in former times. The largest specimen of the species 

 rufa found in the canal bears a very strong resemblance to 

 Binney's figure Melantho subsolida, Anth., but for its pink-tinted 

 interior might be regarded as that species. 



Next may be mentioned Groniobasis (Melania) virginica, 



