32 I Senate 



may find it difficult to break them open, and for tMs reason fewer may be 

 destroyed. Certain it is, that the fragments of the thinner and more fragile 

 shells are far more abundant along the shores of the river. 



Besides the species specially noticed, Dr. Sartwell 'has also sent in 

 this collection many specimens of the other species, in order to increase 

 the varieties, or add to the localities of them in the cabinet of the State. 



The mistakes of Linn^us in making the upper part of a shell the 

 lower, and the anterior part, the posterior, has been for some years cor- 

 rected. It is well known that the base or lower part of bivalves, which 

 have locomotion, as all the naiades, is the opening or orifice on the side 

 opposite to the hinge, and that the common and natural position of the 

 shell is wich the hinge uppermost ; but, for a certain period in summer, 

 many species are often found in pairs near each other, with the hinge side 

 below and inclined to the horizon, and the posterior third or fourth of it 

 standing in the mud, while the animal projects its body in part out of the 

 shell and upwards. The animal holds this position so long that the mud 

 becomes strongly coherent to the hinder part of the shell, so as to be 



washed off with difficulty." 



Your obedient, 



EocHESTER, Dec. 1855. C. DEWEY. 



The following catalogue of the specimens was prepared by the 

 donor, Professor C. Dewey, of Rochester. 



LIST OF NAIADES (CLAMS), 



FOUND IN WESTERN NEW-TORK, AND SENT TO THE STATE COLLECTION 

 AT ALBANY, WITH SOME CHIEFLY PROM OHIO. 



• ■ UNIO, Brug. ; or rather Philipsson. 

 The name signifies a pearl, as pearls are in some species. 

 1 Unio alatus. Say. Dekay's New-York Fauna; Part V, pa, 195. 



U. id 



Lamarck. 



U. 



alatus, 



Lea. 



U. id 



Barnes. 



U. 



id 



Adams, 



U. id 



Hildreth. 



u. 



id 



Dekay. 



U. id 



Conrad. 









Mya alata, 



Wood. 









I send six varieties, male and female; one large m'ale. W 



Genesee river, on the level of Lake Ontario; nacre purple, deep" red, or 

 reddish yellow, splendid. The largest found here, measured in height 

 five inches, and breadth seven. Also in the E ie canal, and the east- 

 ern part of the State. 



