82 



Cincinnati Society of Natural History. 



Pupa contracta Say. Plate IV, A. 



Jaw long and narrow, slightly arched, the ends a little nar- 

 rower than the central part and rounded ; convex margin 

 smooth, concave margin notched, and anterior surface verti- 

 cally striated (Fig. A, 10). 



Radida formula ~ -\- f -j- -J- + f + (ii-i-ii); central 

 tooth with a base of attachment longer than wide, and with 

 the lower outer angles expanded ; reflextion small, narrow, 

 tricuspid; the central cusp rather long, wide, and blunt, the 

 side cusps shorter and sharper; lateral teeth with a wide 

 base of attachment, expanded on the lower outer angle, the 

 reflection narrow and bicuspid, the inner cusp very long and 

 wide, almost reaching the lower margin of the base of attach- 

 ment, the outer cusp about half as long and rather sharply 

 pointed ; marginal teeth low, wide, with from 3 to 7 cusps, 

 the inner cusp being very large and sharply pointed, the 

 others very short. The fifth marginal has 3 cusps, the sev- 

 enth 5 cusps, and the ninth 7 cusps; all of the cusps have 

 will-developed cutting points. Several specimens have been 

 examined, and all agree with the above description (Fig. A). 



Limnophysa columella Say. Plate IV, I. 



Jaws three, the median (superior) elliptical, smooth, or only 

 slightly striated, the lateral jaws irregular, finely striated; 

 cutting-edges brownish black, shading into yellowish black 

 toward the base of the cartilage (Fig. I). 



Radula formula j± + I + f + i + f + i + IT ( 35" 1 " 35); 

 central tooth very small, long, and narrow, the lower outer 

 corners of the base of attachment very much attenuated ; 

 reflexion unicuspid, bluntly rounded; lateral teeth with a 

 quadrate base of attachment, the outer lower corner ex- 

 panded; reflexion long and rather wide, reaching below the 

 base of attachment, bicuspid, the inner cusp very large and 

 long, the outer cusps small and sharp : the inner cusp has a 

 peculiar shape, which is an indication of the third cusp of the 

 transition teeth ; the tenth tooth is tricuspid, and is a transi- 

 tion between the lateral and marginal teeth ; marginal teeth 

 longer than wide, generally four-cuspid, the inner cusp placed 



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