348 THE CHICAGO ACADEMY OF SCIENCES. 



b. Shell bi- or tricarinate 



1. Spiie depressed bicarinata 



2. Spire elevated tricarinata 



143. Valvata sincera Say, pi. xxx, fig. 31; pi. xxxii, fig. 15. 



Valvata sincera SAY, Long's Expedition, p. 264, pi. xv, fig. 11, 1824. 

 Valvata depressa, KUSTER (pars) in CHEMN., ed. 2, p. 88, 1852. 

 Valvata striata LEWIS, Proc. Phil. Acad., p. 260, 1856. 

 Valvata lewisii CURRIER (descr.?) 



Shell: Depressed, more or less discoidal, rather solid; 

 color brownish, transparent to opaque; surface shining, lines 

 of growth numerous, regular, crowded, sometimes encircled 

 by a few spiral lines; apex large, round, almost concealed in 

 the succeeding whorls; spire very flat, almost discoidal; whorls 

 three and one-half, rounded, rapidly increasing, the last consid- 

 erably deflected; sutures impressed; aperture round, continu- 

 ous, whitish or brownish inside; peristome rather thick, simple, 



FIG. 131 



Radula of VALVATA SINCERA Say. (Original.) C, central tooth; 1, 

 intermediate tooth; 2, 3, lateral teeth. 



continuous, the columellar portion being simply appressed 

 against the body-whorl; base rounded, umbilicus round, deep, 

 exhibiting all the volutions. 



Length, 2.50; width, 4.50; aperture length, 1.60; width, 1.75 mill. (10496.) 

 2.25; " 6.00; " " 2.10; " 2.10 " (12141.) 



2.25; " 5.00; " " 2.00; " 2.00 " (12141.) 



Animal: With short, wide foot, bifurcated before and 

 rounded behind; head large; rostrum of good size, with a 

 black line extending down the center of the upper surface; 

 color yellowish-white, transparent; branchia plumose, trans- 

 lucent; eyes black, situated at the base of the tentacles; tenta- 

 cles long and tapering, terminating obtusely. The branchial 

 filament is yellowish-white in color, and is protected by a re- 

 spiratory lobe; the branchial cavity is brownish or blackish. 



Radula formula: l+l+j-i-^+i+i^i-^); (Mus. No. 

 12772); central tooth wider than high, concave on the base 

 and with somewhat attenuated ends; reflection fifteen-cuspid, 



