184 Panama Shells. trochid^. 



Station. — Unknown . 



Habitat. — 'Panama ; C. B. A. ! 



40 specimens were found in the sand. 



VlTRIIVEIilj A. — The number of species and the scarcity 

 of individuals in this genus of minute shells is remarkable. To 

 the 5 species from Jamaica, of which the genus was originally 

 constituted, we now add 12 from Panama. It will be seen, 

 however, that we have only 60 specimens, of which 24 belong 

 to one species, and 13 to another. 



258. Yitriiiella concinna. Nor. sp. 



Shell discoidal : white : with five prominent acute spiral 

 keels, of which one is next below the suture : the second is 

 about equidistant between the suture and the periphery of the 

 last whorl ; the third is a little below the periphery ; the fourth 

 is on the middle of the lower side of the last whorl ; and the 

 fifth is within the umbilicus ; with a more or less distinct ridge 

 between the first two keels ; with curved transverse elevated 

 lines, which become obsolete on the last half of the last whorl : 

 apex minute, papillary : spire nearly flat : whorls three and 

 one-half: planulate above, with the suture subcanaliculate ; last 

 whorl declining near the aperture below the plane of the spire : 

 aperture orbicular, very oblique : lip moderately thickened, 

 slightly angulated by the keels : umbilicus broad and deep. 



Divergence about 175° ; greatest breadth .062 inch ; least 

 breadth .05 inch ; height .03 inch. 



Station. — Unknown. 



Habitat. — Panama ; 0. B. A. I 

 Only 1 specimen was found. 



259. Yitrinella exig^ua, ISTor. sp. 

 Shell subdiscoidal : white : on the periphery of the last whorl 



