[26 J 



armed witt a small, oblique, white tooth on the parietal wall ; 

 peristome simple, regularly arcuate. 



Length 15, diam. 7 mill. 



Put-in Bay Island, Lake Erie. 



Allied to S. Salleana, Pfr., S. Haydeni, W. G. Binney, and 

 espeeiiilly to S. ovalis, Gould. Compared with the latter, the 

 last whorl is less convex, the aperture is more angular above, 

 the columella less arcuate and more distinctly plicate. Three 

 specimens had the parietal tooth mentioned in the description. 

 It is the only North American species in which this tooth has 

 been observed. 



24. Succinea retusa, Lea. 



Plate 2, figure 35. 



Ovateoblorg-, thin and pellucid; .spire moderate, acute; 

 aperture two-tiiirds the total length, elongate ovate, sharply 

 angled above, dilated and retracted below. Light yellowish. 



Length 17, diam. 8 mill. 



Ohio. 



Yery close to ovalis; rather narrower, and differs in the 

 aperture. 



25. Succinea Nuttalliana, Lea. 



Plate 2, figure 26. 



Ovate conic, very thin, pellucid, shining, striate ; spire acute, 

 attenuate; whorls revolving very obliquely; aperture two- 

 tliirds the total length, ovate, broadly rounded below, angled 

 above; columella without fold. Light horn color or greyish. 



Length 15, diam. 8 mill. 



Oregon, California. 



Aperture slightly narrower posteriorly than ovalis. The 

 difference between the two is very slight, but they inhabit 

 different zoolog'cal regions. NuUalliana is rather larger than 

 ovalis. 



26. Succinea Wilsonii, Lea. 



Plate 3, figure 37. 



Elongate-oblique, striate, thin, diaphanous ; spire prominent, 

 acute, suture well impressed ; whoxls 4, rather, convex, not 



