74 
aperture round, continuous; peristome simple, continuous, inner 
portion being pressed against the wall of the preceding whorl; 
umbilicus round, deep, showing all the yolutions. 
H. 2*25 W. 3-5 A.H. 1-25 A.W. 1*25 
Locality. Colton lake. 
This little shell is not as common as Valvata tricarinata. 
It varies considerably in height and width, but has a very 
characteristic appearance. An occasional V. tricarinata lacking 
the carination of the whorls might be confused with it, but the 
whorls of V. sincera are more completely rounded. 
Valvata tricarinata Say 
Plate VIII, figures 23a-23f 
Shell translucent, tinged with green; surface shining, lines 
of growth numerous, fine; spire elevated; whorls three to three 
and a half, rapidly and regularly expanding, strongly carinated ; 
usually three carinae are present, one on the base of the shell, 
one on the periphery, and one on the shoulder of the whorls, 
.but one or more of these may be absent; aperture rounded ; 
continuous; columella straight; base of shell rounded or keeled; 
umbilicus round and deep, 
H. 2-7 W. 3-9 A.H. 1-8 A.W. 1-65 
Locality. Marl beds, McKay lake and throughout the 
Ottawa valley. 
This species is very abundant in the marl deposits. The 
figures show well the great variation in the carination of this 
form. The marl specimens are much smaller than the forms 
living to-day. Walker 1 has divided this species into several 
varieties, normalis, perconfusa , simplex , etc., but as these marl 
forms merge into each other, in this paper such varieties are 
not differentiated. 
1 Walker, Bryant, “ Revision of the Carinate Valvatas of the United 
States.” Nautilus, vol. 15, No. 11, pp. 121-125. 
