172 MOLLUSCA. 



length 75mm., height 53mm., breadth 39mm., the largest female: 

 length 70mnl., height 49mm., breadth 42mm. The average specimen 

 is considerably smaller. 



99. Lampsilis multiradiata (Lea).- — A single female specimen of 

 this shell was ol^tained from the lower portion of the Pigeon River 

 (21). It measures: length 58mm., height 36mm., breadth 23mm. 



100. Lampsilis luteola (Lamarck). — ^This was the most abundant, 

 widely distributed and variable unione in the region studied. The 

 small Great Lakes form was found exceedingly abundant along the 

 unprotected, sandy shores of Sand Point (5). It was also obtained, 

 but in lesser numbers, from the protected sedge marshes (7) and the 

 deep littoral habitat (1) off Sand Point, and the unprotected, sandy 

 beaches of Stony Island (5) and near Little Oak, and Hat Points (5). 

 The largest examples measure: male, length 64mm., height 37mm., 

 breadth 23.5mm.; female, length 52.5mm., height 34.5mm., breadth 

 20mm. 



The large river form occurred in considerable numbers in the lower 

 portion of Pigeon River (21) and in the ox-bow pond (22) off the 

 river near its mouth, and in small numbers in Rush Lake, in places 

 where the bottom is mucky (11) or marly (13) and off Dune Point 

 (15) where the bottom is sandy with a very thin layer of marl. The 

 largest examples measure: male, length 119mm., height 66mm., 

 breadth 42.5mm.; female, length 101mm., height 63mm., breadth 

 36.5mm. The specimens from Rush Lake are smaller; the largest 

 specimen, a male, measures 86.5mm. in length. 



As will be seen from the above measurements, the males in this 

 region appear to attain a greater size than the females; this is true 

 both in the thirty-odd specimens collected from the Pigeon River 

 and in the specimens from Sand Point, which number about one 

 hundred. 



The few shells collected from Rush Lake were found entirely buried 

 in the light muck, each with only a funnel-shaped cavity about four 

 inches deep leading down to the siphons. When disturbed in this 

 position, the mollusc, by suddenly ejecting water, caused the sides 

 of the funnel to cave in and completely bury it. The ejection of the 

 water appeared to be done by the sudden closing of the valves, as is 

 common among bivalves when disturbed. 



101. Lampsilis recta, var. sageri (Conrad). — A single male speci- 

 men of this Great Lakes form was obtained from shallow water along 

 the unprotected sandy shore of Sand Point (5) off Twin Bars. It 

 measures: length 87mm., height 37mm., breadth 20mm. The beaks 

 are quite heavily eroded. 



102. Lampsilis nasuta (Say). — This species was found quite 



