[24] 

 18. Succinea rusticana, Gould. 



Plate 2, figure 19. 



Elongate ovate, thin, fragile, diaphanous, irregularly striate ; 

 spire elevated, acute, suture moderately impressed; whorls 3, 

 not very convex ; body long, oval, not inflated ; aperture nar- 

 rowly oval, three-fifths the entire length. Pale greenish or 

 yellowish. 



Length 14:, diam. 7 mill. 



Oregon, California. C5o'linT,(3:^'' -T'''''>';^a/. 



Immediately distinguished from the other species of this 

 section, by its narrow, lengthened form. Kesetubling the fol- 

 lowing several species, but diftering from them all in the 

 regular curve of the outer lip. 



*** Shell ovate, spire rather elevated, apex acute, whorls 

 flattened, hoily ivhorl larrje, hut not inflated, aperture an- 

 gulate above, lahvcm svperiorhj more or less flattened. 



(BRACHYSPIRA, Pfeiffer.) 



19. Succinea Haydeni, W. G. Binney. 



Plate 2, figure 20. 



Elongate-oval, thin, shining; spire short, acute; whorls 3, 

 convex, the last marked with wrinkles of growth, and irregu- 

 lar, heavy, spiral furrows ; aperture oblique, oval, five-sevenths 

 the total length, the lower margin considerably expanded. 

 Amber colored. 



Length 21, diam. 9 mill. 



Nebraska and northwards. 



The peristome is more flexuose than in S. ovalis, Gld., and 

 it is more attenuately pointed above; it also difl'ers in having 

 the revolving lines, and is a larger species. 



Yar. minor. Length 15 mill. 



20. Succinea Sillimani, Bland. 



Plate 2, figure 21. 



Oblong-ovate, thin, coarsely striate, shining ; spire short, 

 acute, suture impressed; whorls 3, convex, much flattened 

 superiorly; aperture oblique, elongate oval, angular above, 

 eft'use at base, columella slightly arcuate, with a thread-like 

 thickening above. White? 



