73 
This small shell is rather uncommon in this area and seems 
to merge gradually into the variety next described. 
Amnicola limosa porata Say 
Plate VIII, figures 22b-22f 
This form is very similar to the above species, but differs 
in being more globose; the whorls are more swollen and the 
umbilical opening is larger and more rounded. 
H. 4-2 W. 3-5 A.H. 2-23 A.W. 1-75 
Locality. Marl beds, McKay lake and throughout the 
Ottawa valley. 
This species is, with Valvata tricarinata, by far the most 
common form in the marl faunas. It is very uniform in size, 
but the shells in these marl beds are somewhat smaller than 
those living to-day. Its very globose shape makes this stout 
little shell easily recognized. 
Amnicola lustrica Pilsbry 
Plate VIII, figures 20a-20d 
Shell thin, acutely turreted, surface shining; lines of growth 
minute, numerous; whorls five to six, well-rounded, increasing 
regularly; sutures much impressed; spire elongate; aperture 
roundly ovate; peristome thin, continuous, slightly reflected ; 
base of shell rounded; umbilicus small, round, and deep. 
H. 4-0 W. 2-0 A.H. 1-5 A.W.M5 
Locality. Colton lake. 
This species is readily distinguished from other Amnicolidce 
by its very slender shell. Though fairly abundant, it is much 
less common than A. porata. 
Valvata sincera Say 
Plate VIII, figures 2 la-2 lb 
Shell depressed, discoidal; surface shining, lines of growth 
numerous, fine, crowded; apex large, spire flat; whorls rounded 
three to three and a half expanding gradually, rapidly, the last 
whorl being deflected downward; sutures deeply impressed; 
