126 THE NAUTILUS. 



NEW SPECIES OF ANCYLIDJ3. 



BY BRYANT WALKER. 



Neoplanorbis smithii n. sp. PI. IX, figs. 1 and 2. 



Shell minute, planorboid, perforate, slightly convex above and 

 below ; periphery obtusely angulate ; thin, translucent, whitish, shin- 

 ing with a silky luster from the fine, closely set, regular lines of 

 growth. No trace of spiral sculpture. Whorls 2, rapidly enlarging ; 

 apex sunken ; the last half of the first whorl elevated above the out- 

 line of the body whorl ; apical whorl convex, the convexity rapidly 

 diminishing towards the aperture ; suture well impressed, rising 

 somewhat at the aperture ; aperture large, oblique, slightly ex- 

 panded, equally curved above and below ; columellar margin dilated, 

 straight and vertical, callously thickened below, smooth ; umbilicus 

 a mere perforation. 



Alt. 1, diam. 2 mm. 



Types (No. 27149, Coll. Walker) from the Coosa river at Hig- 

 gin's Ferry, Chilton Co., Ala. Co-types in the collection of T. H. 

 Aldrich, Geo. H. Clapp, John B. Henderson, Jr., and the Phila- 

 delphia Academy. 



This little species differs from tantillus and all the other known 

 forms of the genus by the entire absence of spiral sculpture and the 

 elevation of the spire above the level of the body whorl. The animal 

 is black and the shell consequently appears of that color until cleaned. 



Neoplanorbis umbilicatus n. sp. PI. IX, figs. 3 and 4. 



Shell minute, planorboid, umbilicate, convex above and below, 

 but flattened above as it approaches the aperture and obliquely flat- 

 tened below the periphery ; periphery obtusely carinate ; brownish 

 horn-color ; lines of growth fine and regular ; surface sculptured by 

 raised spiral lines, which are heavier below than above the periphery. 

 Whorls 2, rapidly enlarging, apex sunken ; apical whorl very con- 

 vex ; body whorl nearly flat in the sutural region, but curving down 

 rapidly toward the peripheral carination ; suture well impressed and 

 depressed below the periphery at the aperture ; aperture large, 

 wider than high, flattened above and below, the upper and lower 

 margins being nearly parallel, obliquely flattened below the per- 

 iphery ; columellar margin broadly dilated, curved and partially 



