lOUO DR. J. E. GRAY ON A NEW GENUS OF MOLLUSKS. [DcC. 12, 



(and sometimes two or three) to the cavity of one or more shells of a 

 species, so that there is no doubt of the operculum belonging to that 

 species ; but in general, as he kept his shells lying loose on cotton- 

 wool, so he placed the opercula on the cotton-wool under the shells 

 to which they belonged. Unfortunately, under these circumstances, 

 an operculum becomes easily separated from its shell, as must have 

 occurred in this case. Sometimes he preserved more opercula than 

 specimens of the shell ; but in this case there is only one operculum 

 of the form in the drawer. The operculum is no accidental varia- 

 tion of either of the other forms ; it is destitute of the two diverging 

 rays which are so characteristic of each of them. In the angularity 

 of the lower edge, compared with the rest of the shelly plate, it is 

 between the two forms before described. In its very wide cartilagi- 

 nous flap it is like the second form, or that of the genus Stenopoma. 



9. Description of Saulea, a New Genus of Ampullariada from 

 Sierra Leone. By Dr. J. E. Gray, F.R.S., V.P.Z.S., &c. 



The British Museum has received a specimen of Ampullaria from 

 Sherboro, near Sierra Leone, where it was collected. It differs from 

 all the species of the family in being beautifully variegated, and 

 more like a terrestrial Bulimus than a freshwater shell. It is, at 

 the same time, peculiar for the thinness of the shell and operculum, 

 these not being thicker than thin writing-paper. 



The regularity of the colouring shows that it is not an accidental 

 variation, but a normal state of the species. 



The species is also well marked by its form, having a more pro- 

 duced conical spire than most of the species of the genus, and the 

 upper whorls of the spire are peculiar for being obscurely keeled. 

 The keel gradually becomes less visible, and the later ones regu- 

 larly rounded. 



Saulea vitrea. 

 Saulea. 



Shell ovate, subglobose, very thin, parchment-like, clastic, dark- 

 coloured, covered with a very thin, hard, olive periostraca. Spire 



