19 



pressed and subulate ; base broadly curved ; hinge line 

 straight, less than the greatest length of the shell; a line 

 or groove on the inner margin extending from the beak to 

 the posterior extremity ; beaks very small, near the ante- 

 rior end ; umbonial region gibbous. Surface marked by 

 distinct, regular, imbricating lamellas. 



Length from one-eighth to three-fourths of an inch. 



Locality. — Spergen Hill ; Bloomington, la. ; Alton, 111. 



£/Cypricardia subplana. — Shell ovate oblong ; anterior end 

 very short ; posterior end extremely elongate, very gradu- 

 ally narrowing to the extremity which forms a symmetrical 

 elliptic curve ; cardinal and basal margins nearly parallel ; 

 beaks small ; umbonial region depressed convex. A few 

 obsolete concentric folds visible on the surface ; intermedi- 

 ate portions, probably, finely striate. 



Length, '69, width *38 of an inch. 



Locality. — Spergen Hill. 



EUOMPHALUS, Sowerby. 



* Euomphalus quadrivolvis. — Shell planorbicular, spire 

 depressed, composed of about four turns, the inner one 

 scarcely rising above the last volution; volutions somewhat 

 rapidly increasing from the apex, regularly rounded ; aper- 

 ture round-oval, slightly transverse ; umbilicus less than the 

 diameter of the outer volution. Surface marked by fine, 

 closely arranged strise of growth. 



Diameter *12 to *31 ; elevation '06 to *16 of an inch. 



Locality. — Spergen Hill, Bloomington. 



l - Euomphalus Spergexensis. — Shell sub-discoid or planor- 

 biform ; spire composed of five or six turns, the inner ones 

 coiled in the same plane, two or three of the outer ones only 

 visible in profile ; suture well defined on both sides ; volu- 

 tions rounded below with a distinct obtuse angulation on 

 the upper side, a little distance from the suture ; umbilicus 

 nearly twice the breadth of the outer volution ; aperture 



