SYNONYM. 



U. GLEBULUSj Nob. Transifhama JournaL Vol 4, 

 p. 526. 



DESCRIPTION. 



Shell transversly oval orbicular, sometimes subovate, very 

 convex, dark brovs^nish : umbones not elevated above the 

 general curvature : beaks not prominent, (mucli eroded, 

 exposing a wax yellow^ surface :) hinge and basal margins 

 correspondingly arquated ; destitute of any prominent an- 

 gle : anterior aad posterior margins almost equally arqua- 

 ted ; the former extending a little with age into a more or 

 less obtuse angle at the extremity of the umbonial slope : 

 umbonial slope slightly elevated : lunule not dilated : imtlt- 

 ina. little tinted with rosaceous : cardinal teeth deeply and 

 approximately granulated and sulcated : lateral teeth remote 

 from the cardinal teeth, remarkably granulated ; length 

 hardly greater than their distance from the cardinal teeth ; 

 posterior accessory cicatrix small and approximate. 



OBSERVATIONS. 



The transverse simple rotundity of this shell, com- 

 bined with the much sulcated cardinal teeth and the re- 

 mote, short lateral teeth, readily distinguish it Sev- 

 eral specimens were sent to me by Mr. Barabino, as in- 

 habiting the same locality with the preceding. 



REFERENCE TO THE PLATE. 



Tlie plate represents cxteriur, interior and back vie'.vs. 

 PI. 34. 



