106 PROCEEDINGS OP THE ACADEMY OF 



times rare. Smaller shells abound along water-margins on the 

 hill regions south, at Little Lakes, and at Schuyler's Lake. Dr. 

 Brown finds it in Litchfield. 



Succinea obliqua, Say. 



Damp, shaded grounds along the Mohawk. This species is 

 sometimes found on vegetation and trees, several feet from the 

 ground. S. Tolfeniana, Lea, has similar habits, and has been found 

 on apple-trees or hill-sides near woods. 



Succinea ovalis, Gould. 



Margins of ditches, river banks, lake-shores, &c. Sometimes 

 very abundant. 



Succinea Totteniana, Lea. 



Inhabits ravines and hill-sides, wooded. Is nearly as large as 

 obliqua, and has similar arborial habits. 



Trypanosoma subulare, Lea. 



Erie Canal and Mohawk River. Prefers still water and a muddy 

 slope. Very abundant. 



Unio cariosus, Say. 



Mohawk River and Erie Canal. Scarce. 



"Unio complanatus, Lea. 



Canal, rivers, muddy streams, &c, but not in lakes. Our most 

 abundant species. 



Unio lutiolus, Lam. 



Mohawk River. Erie Canal, rarely. It is probably more abun- 

 dant in the river a few miles below Little Falls. 



Unio radiatus, Lam. 



Lakes. The only Unio found in Little Lakes and Schuyler's 

 Lake, though complanatus occurs in the outlet of Schuyler's Lake, 

 and in streams emptying into the lake. 



Unio Tappanianus, Lea. 



Mohawk River. Abundant only at times. Some cause not un- 

 derstood makes them scarce only in exceptional seasons, as is the 

 case with many other molluscs. 



Valvata tricarinata, Say. 



Erie Canal, Mohawk River, Schuyler's Lake, and Little Lakes. 

 In " Little Lakes" the shells are varied ; bicarinata and simplex, 

 occurring as prevailing forms in the upper lake ; along the marshy 

 borders V. sincera, Say, occurs. I am disposed to believe sincera 



