MARGINELLA 



TESTA ovato-oblonga, laevis; spird brevi^ non- 

 iiiiiiquam paene occulta : apertura elongata^ basi 

 einarginulata ; lahio externo incrassato^ revoluto; 

 columella versus basim plicata. 



Placed by Linne among- his Volutae, and by Bruguiere 

 among- his Mitras, but well distinguished by Lamarck from 

 bothj the peculiar character from which he has named it, 

 being the thickened and revolute outer lip. The Margi- 

 nellae are marine, and though not absolutely internal shells, 

 the mantle of their animal is capable of extension over the 

 whole outer part, where it appears to be constantly de- 

 positing shelly matter, so that they are always smooth and 

 shining, and sometimes very thick. They are all very neat 

 small shells, and mostly prettily coloured. 



Shell ovato-oblong, smooth, with a short, in some spe- 

 cies almost hidden, spire; aperture elongate, narrow, rather 

 wider at the lower than at the upper part, slightly notched 

 at the base ; outer lip thickened and turned outwards ; this 

 thickened outer lip appears to be formed but once during 

 the life of the animal, of course at the time of arriving at 

 its adult state, after which it only increases the thickness 

 of its shell. Several folds are very distinct at the lower 

 part of the Columella ; the number and disposition of these, 

 added to the either distinct or almost hidden spire, seem 

 to point out two natural sections in this Genus, which 

 may be characterized in the following manner : 



§ 1. Spira brevi, distincta, plicis quatuor ad basim 

 columellsB ; to this first section belong the Volutes Glabella, 

 Dactijlus^ guttata^ Faha^ picta. &c. ; and our English 

 species, Voluta IcBvis, Don. or Cypr(Ea Voluta^ of Mont. : 

 though, in this last, the plaits on the columella are very 

 indistirxt. 



§ S. Spira pcsne occulta, basi columellaj plicataltl, 



