160 



fishes he called it AracTinactis hracMolata. A full account of this 

 Actinia will soon be published in the publications of the Society. 

 Living specimens were brought to the Society for examination, and 

 also larvae of starfishes to compare with them. 



Prof. "William B. Rogers presented a paper by Dr. J. S. 

 ISTewberry, entitled "Descriptions of the Fossil Plants col- 

 lected by Mr. George Gibbs, Geologist to the United States 

 North West Boundary Commission under Mr. Archibald 

 Campbell, United States Commissioner. Referred to the 

 Publishing Committee. 



The Secretary read the following communication from Dr. 

 James Lewis, of Mohawk, N. Y. : — 



Since the autumn of 1853 I have devoted some attention to the 

 mollusks of this immediate vicinity. My explorations and search- 

 ings for species and varieties have been, from the first, quite thorough, 

 and have, I think, developed the fact that the number of aquatic spe- 

 cies is being increased by the introduction of species from other parts 

 of the State ; while our local land species, if undergoing any change, 

 must be diminishing, by reason of changes in the face of the country, 

 making their former habitats untenable. 



I propose to offer some remarks upon some aquatic species detected 

 under such circumstances as to lead to the inference that they have 

 been introduced. 



Up to 1855 and 1856 the following species had not been detected, 

 although as much and perhaps more attention had been devoted to 

 minute search than since. 



Paludina rufa Haldeman. Observed 1856. 



Melania virginica Gmel. " 1858. 



Melania? isogona Say. " 1862. 



Sphasrium solidulum Prime (var. distortum) " 1860. 



Paludina eufa Hald. was first detected in the Erie canal within 

 a somewhat restricted area, where it has been found since in consid- 

 erable numbers, and of such a size as indicates a growth of five or 

 six years (1860). This would date its introduction back at least to 

 1854 or 1855. Two years later, specimens which might have been 

 developed in two or three years were found, but not very plenty 

 (1856). Since that time (perhaps as early as 1857), a very few 

 specimens were found in the Mohawk Kiver, small, and of a some- 

 what different form and color from those found in the canal. Later 

 (1862), they have been found there larger and more abundantly. The 

 soft parts of this species present constant characters which separate 



