178 CONTRIBUTIONS 



Observations. This species differs from the last in 

 being broader, in having a shorter spire, in having one 

 fold less, and in being thicker in the lip. 



M. plicata. Plate 6. Fig. 189. 



Description. Shell ovate, longitudinally folded above ; 

 substance of the shell rather thick ; spire short, rounded 

 at the apex ; whorls three, flattened above ; columella 

 with six folds ; mouth narrow, curved ; outer lip thick, 

 finely crenulate within. 

 Length 5-20ths, Breadth 3-20ths, of an inch. 



Observations. Differs from all the species herein de- 

 scribed, in having longitudinal folds, which are placed on 

 the superior part of the whorls. 



M. semen. Plate 6. Fig. 190. 



Description. Shell ova to-elliptical, polished ; substance 

 of the shell rather thick ; spire very short and rounded at 

 the apex ; whorls three, flattened above ; columella with 

 six folds ; mouth narrow, curved ; outer lip somewhat 

 thick and very minutely crenulate within. 



Length 5-20ths, Breadth 3-20ths, of an inch. 



Observations. This species seems most analagous to the 

 last described, but is without its exterior folds, and is more 

 elliptical. 



