174 MOLLUSCA. 



off the Pigeon River. An example measures: length 141mm., 

 height 69mm., breadth 54.5mm. 



111. Alasmidonta calceola (Lea).^ — This species appeared to be 

 very rare in this region, only one specimen being found. It was col- 

 lected on Little Oak Point, where it had been washed up alive into 

 very shallow water on the bare sand beach (5) apparently from some- 

 what deeper water. The shell is quite small, being only 26mm. long, 

 and is quite thin; the beaks are very heavily eroded, the left valve 

 being worn thru in two places. 



112. Unio gibbosus Barnes. — A single valve of this species was 

 picked up along the sandy unprotected shore of Sand Point (5) and 

 an entire specimen was obtained from a similar locality on Stony Is- 

 land. Both are the small Great Lakes form: one of the shells meas- 

 ures: length 60mm., height 31mm., breadth 31mm. 



113. Quadrula undulata (Barnes). — A few dead shells of this 

 species were obtained from the Pigeon River, both in the upper and 

 the lower portions (23, 21). It seems probable that the shell is still 

 living in the lower part. An example measures: length 94mm.. 

 height 73mm., breadth 31mm. 



114. Quadrula rubiginosa (Lea). — A single dwarfed shell of this 

 species was obtained from the lower portion of the Pigeon River (21). 

 It measures: length 49mm., height 37.5mm., breadth 20.5mm. 



Sphaeriidae. 



115. Sphaerium solidulum (Prime). — ^This species was found in 

 considerable abundance among algae, principally consisting of Vauch- 

 eria, along the banks in both the upper and the lower portions of the 

 Pigeon River (23, 21). The largest shell measures: length 11.5mm., 

 height 9.5mm., breadth 7mm. 



116. Sphaerium striatinum (Lamarck). — ^This species was collect- 

 ed, together with the preceding species, but in lesser abundance, 

 from both the upper and the lower portions of the Pigeon River (23, 

 21). The largest shell measures: length 11.5mm., height 8mm., 

 breadth 5.75mm. 



117. Sphaerium sulcatum (Lamarck). — Considerable numbers of 

 this shell were obtained from Rush Lake, on the gravelly and sandy 

 bottom off Raymond's, Dune, and Fourth Points (14, 15, 16). It 

 was not found in .such abundance as Sphaerium flavum off Ray- 

 mond's Point, but this was the only habitat where the latter was 

 found. A representative example measures: length ISmm., height 

 12.5mm., breadth 9mm. 



118. Sphaerium OGcidentale Prime.— Together with Lymnaea pal- 

 ustris and Musculiiun truncatum, this species appeared to be one of 



