165 



Species with aperture as long as the shell ; spire not pro- 

 jecting, sometimes sunk or umbilicated. 



M.faha. The Bean Marginella. 



Species with aperture shorter than the shell, and the spire 

 projecting. 



M. ccerulescens. The cerulean Marginella. 

 Species with surface bluish white ; spire short and acute ; 

 four plaits on the columella ; interior lip brownish purple. 



5. Volvaria. Five species. 



The connecting genus between those shells that have a 

 columella and those that are evolved upon their own axis. 

 Distinguished from the Marginella by not having a thickened 

 outer lip. The shells are marine, and generally very small. 



Shell cylindrical, convolute ; spire obsolete or concealed ; 

 aperture narrow, the whole length of the shell, with one or 

 more plaits on the columella at the lower part. 



Volvaria monilis. Volvaria triticea. 



V. pallida. V. oryza. 



V. miliacea. 

 V. monilis. The Necklace Volvaria. PI. 29, fig. 5. 

 Species greatly involuted ; aperture very narrow and very 



