140 THE NAUTILUS. 



concave posterior slope. It stands nearest to A. Jilosus from which 

 it differs by the nearly central, acute apex, proportionately longer 

 and concave posterior and less convex anterior slope and smooth 

 surface. It is so entirely different in shape from rhodacme that 

 there is no danger of confounding them. 



The two specimens from Kentucky, received by the Am. Mus. 

 of Nat. Hist, from Anthony as A. elatior are apparently identical 

 with this species (see Naut. XVIII, p. 79). 



ANCYLUS (L^EVAPEX) HEMISPHjERICUS n. sp. PI. ix, figs. 14, 15 

 and 16. 



Shell obtusely elevated, broadly oval or subcircular, sides almost 

 equally rounded ; apex subcentral, very obtuse and only slightly in- 

 clined toward the right ; smooth, light yellowish horn color; anterior 

 slope very convex, posterior somewhat less so ; lateral slopes about 

 equally convex, the left being as usual, somewhat the longer ; 

 lines of growth rather prominent and irregular, more or less rippled 

 by subobsolete, irregular radial striae. 



Length (type) 3.5, width 3, alt. 1.5 mm. 



Length (cotype) 3.8, width 3.1, alt. 1.8 mm. 



Length (Decatur) 4.1, width 3.25, alt. 1.8 mm. 



Types (No. 20785 Coll. Walker) from Georgia. Cotypes in the 

 collections of the Kent Scientific Museum, Grand Rapids, Mich., 

 and the Philadelphia Academy. Also from Decatur, Alabama. 



The type lot formed part of the DeCamp collection now in the 

 Kent Scientific Museum. Unfortunately no definite locality is 

 given and no further information as to the history of the specimens 

 is attainable. 



This species is very distinct by its globose, almost hemispherical 

 shape. None of the shells have a perfect apex. 



The type is not quite full grown, but was selected as being less 

 eroded and showing more exactly the contour of the shell. The 

 other measurements given are from mature shells which show the 

 length and width accurately, but owing to erosion are proportionately 

 less elevated. With the erosion of the apex the anterior and 

 posterior slopes have nearly the same convexity, and the specific 

 name adopted becomes even more appropriate than in the type. 



The specimens from Decatur, Ala., also collected by De Camp, are 

 slightly larger and heavier than the types, but evidently the same 

 species. 



