4.2 



153. Calyculina partumeia Say. In pools and ditches, 



common, small. It is noteworthy that 

 almost every place has its own, rather 

 constant form. Yet a part may be distinct. 



154. Calyculina securis Pr. var cardissa Pr. (teste 



Roper). Pools and ditches, less common 

 than the preceeding. A large, strongly in- 

 flated form, usually of a vivid yellow, the 

 surface dull ; variable. 



155. Pisidium compressum Pr. Common in the river, 



creeks, races and the canal, and in pools filled 

 by. freshets; variable in shape and striation. 



156. Pisidium fallax Sterki. River and creeks, rather 



common. 



157. Pisidium cruciutum Sterki. River, rather 



common. One of the most characteristic of 

 all Pisidia. 



158. Pisidium punctatum Sterki. River, not rare; 



most specimens typical, with ridges on the 

 beaks. The smallest of our species. 



159. Pisidium variabile Pr. Rather scarce, in different 



places. 



160. Pisidium nov-eboracense Pr. Spring-brooks, 



ditch from swamp; rare in the river. 



161. Pisidium sargenti Sterk\. Rather scarce. 



162. Pisidium walkeri Sterki. Side-cut on mill race, 



not common, but very good, typical 

 specimens. 



163. Pisidium abditum Hald. Ditches and pools, 



common and variable. 



164. Pisidium politum Sterki. Common in ditch from 



swamp, where the types were found, mill race 

 and other places. 



165. Pisidium splendidulum Sterki. Ditches, not 



common. 

 (All these Pisidia are good, well characterized 

 species, and distributed over a large part of the 

 country ). 



