176 MOLLUSCA. 



were obtained among algae in the Pigeon River (22) and from an old 

 stone quarry (20) near Little Oak Point. One of the former measures: 

 length 3.25mm., height 2.75mm., breadth 2mm. 



125. Pisidium compressum Prime.- — A single living specimen of 

 this shell was collected off Dune Point (15) in Rush Lake. It meas- 

 ures: length 2.5mm., height 2.25mm., breadth 1.5mm. 



126. Pisidium compressum, var, rostratum Sterki. — A single valve 

 of this form was collected off Dune Point (15) in Rush Lake. It 

 measures: length 3mm., height 2.5mm., breadth (estimated for the 

 complete shell) 2mm. 



127. Pisidium variabile Prime. — A few dead specimens of this 

 shell were found off Dune Point (15), in a somewhat muck-covered 

 portion. One measures: length 3.5mm., height 3.5mm., breadth 2.5 

 mm. 



128. Pisidium vesiculare Sterki. — A small number of specimens, a 

 very few of which were living, were obtained from shallow water off 

 Dune Point (15). An example measures: length 2.25mm., height 

 2mm., breadth 2.25mm. 



129. Pisidium splendidulum Sterki. — This shell appeared to be 

 the most abundant species of Pisidum in the places where it occurred. 

 It was found in considerable numbers off Dune Point (15) and in 

 lesser numbers off Fourth Point (16). An individual measures: 

 length 2.25mm., height 2mm., breadth 1.5mm. 



130. Pisidium roperi Sterki. — A few individuals of this species 

 were obtained from a tamarack swamp (42) near Rush Lake, A 

 representative example measures: length 3.75mm., height 3mm., 

 breadth 2.25mm. 



131. Pisidium medianum Sterki. A few specimens were obtained 

 from Rush Lake, off Dune Point (15). Dr. Sterki notes that some 

 of these are somewhat deformed. One of the more typical shells 

 measures: length 2.5mm., height 2.25mm., breadth 2.5mm. 



132. Pisidium strengii Sterki. — A few dead valves of this species 

 were obtained from the shallow water off Dune Point (15) in Rush 

 Lake. An example measures: length 2.5mm., height 2mm., breadth 

 1.5mm. 



Pisidium sp? — A few indeterminate valves were collected from 

 Dune Point (15) in Rush Lake. 



Ann Arbor, Mich., June, 1910. 



