OF NORTH AMERICA. 459 



shouldered appearance to the whorls, rapidly increasing in size, the 

 last whorl being inflated with numerous rather marked transverse 

 costse, minutely wrinkled; suture somewhat deep, regularly impressed; 

 aperture elongately ovate, effuse, approaching patulous, pearly white 

 within; outer lip simple, the margin connected by a slight calcareous 

 deposit; columella somewhat twisted, but straight in front." (Call). 

 Length. Breadth. Aperture length. Breadth. 

 13.40 7.10 9.00 5.90 mill. (Call.) 



16.82 8.88 " 



13.40 7.10 .... .... average of 9 spec. (Call). 



SHELL : Varying from globose to elongate-ovate, rather solid ; 

 color (of dead shells) white; surface dull, lines of growth heavy, wide, 

 somewhat regular and in some cases equidistant; surface of body 

 whorl with numerous heavy, rounded, irregularly placed ribs or costae ; 

 the surface is minutely wrinkled but distinct spiral lines cannot be seen 

 in the specimens examined; apex small, smooth, roundly flattened, 

 spermaceti white in color; whorls 4-4 */2, convex, rapidly enlarging, 

 sometimes slightly shouldered; spire broadly or sharply conic, varying 

 in length from one-third to one-half the length of the shell, flattened 

 or pointed in different specimens; sutures deeply impressed; aperture 

 varying from round to elongate-ovate, in some specimens somewhat 

 effuse; peristome thin, sometimes internally thickened; parietal wall 

 with a heavy callus which is more or less erect, leaving a well-defined 

 umbilical chink; axis thickened, only slightly twisted and with a faint 

 plait. (Phil. Acad. specimens). 



Length. Breadth. Aperture length. Breadth. 

 14.50 10.00 9.50 4.50 mill. Type, Smithsonian. 



9.25 6.00 5.50 3.10 " 



16.25 8.50 9.00 4.50 " Phil. Acad. (62603.) 



14.00 8.00 8.25 4.75 " 



10.50 6.50 6.00 3.75 " 



9.50 6.00 5.50 3.50 " " 



TYPES: Smithsonian Institution, four specimens, No. 31276. 



TYPE LOCALITY: Lake Utah, Lehi, Utah. 



ANIMAL, JAW, and GENITALIA : Not recorded. 



RADULA : Call says, "The dentition differs from typical R. ampla 

 Mighels very materially," but he does not say in what manner. In 

 another place (T. c. pp. 47, 48) he says, "dentition unpublished." 



RANGE: Utah. The relation of this species to the fauna of the 

 ancient Lake Bonneville is not clearly known. There is reason to be- 

 lieve that it is a descendant of the Pliocene Lymncea Kingii. From 

 the records it would seem that it is a new species evolved since the dep- 



