OCR Text |
Show 1000 DR. J. E. GRAY ON A N E W GENUS OF MOLLUSKS. [Dec. 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 cottonwool, 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 variation 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 cartilaginous flap it is like the second form, or that of the genus Stenopoma. 9. Description of Saulea, a N e w Genus of Ampullariadce from Sierra Leone. By Dr. J. E . G R A Y , 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 produced 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 regularly rounded. Saulea vitrea. S A U L E A. Shell ovate, subgiobose, very thin, parchment-like, elastic, dark-eoloured, covered with a very thin, hard, olive periostraca. Spire |