172 College of Forestry 



63. Valvata bicarinata normalis Walker. 



Small forms referable to this race or variety occurred spar- 

 ingly in a few habitats, on gravel, sand, clay, and mud bottoms, 

 associated v^dth algae (Cladophora, etc.) in water two to five 

 and a half feet deep. 



*64. Valvata sincera (Say). 



Sincera is a deep water form and occurred on gravel and 

 mud bottoms in water 11^ to 18 feet deep, usually associated 

 with the alga Cladophora fracia. It was most abundant in 

 water 15 and 18 feet deep. 



ORDER PULMONATA 



Family PiiYsiDyE 

 Genus Physa Draparnaud 



65. Physa warreniana Lea. 



This tadpole snail occurred on all varieties of bottom in 

 water from one-half to eleven and one-half feet deep. It is 

 abundant, however, only in water one-half to one and a half 

 feet deep, and the numbers decrease with depth. A gravel or 

 boulder bottom is the normal habitat of this species when adult, 

 but when young or immature, as was the case with the greater 

 part of the individuals collected (1-3 mm.), it lives in fila- 

 mentous algae {CEdogoninm, Cladophora, Spirogyra). Of 47 

 lots collected but six contained adult animals. This is another 

 species which attains its maturity in the fall, adults being 

 abundant the previous year, in September, in shallow water 

 where but few immature shells were seen. 



Many individuals of warreniana occurring in Lower South 

 Bay have the spiral sculpture reduced to a few faint lines. In 

 some specimens this sculpture may be wanting entirely, the 

 surface being smooth and shining. There is also some varia- 

 tion in the height of the spire and in the width of the shell. 

 A few individuals are miniature examples of Physa sayii as 

 figured by Binney ('65, p. 80, fig. 136). It is evident that 

 absence of spiral sculpture is not a safe criterion alone with 



