OF HARTING. 321 



Fragile Moss Shell (Balea perversa), one of our com- 

 monest, may be collected in great numbers on the 

 mossy bark of the old beech trees in the park. 



The Epiphragm, where it is found in the Helicidcs > 

 is a thin plate accurately fitting the mouth of the shell, 

 and secreted by the animal for its protection during 

 periods of inactivity, but is cast off at will when no 

 longer required. The Operculum, as in the Common 

 Winkle for instance, is a plate of a horny character 

 (in some Genera it is calcareous) permanently attached 

 to the back of the animal's foot, and naturally closes 

 the aperture of the Shell when its inhabitant has 

 retired within it ; but the next genus we have to 

 notice is characterized by the possession of an ap- 

 paratus for (partially) closing the last whorl of the 

 shell within the mouth, which is neither epiphragm 

 nor operculum. It consists of a valve attached to the 

 pillar of the shell by an elastic hinge, and " When the 

 animal wishes to protrude itself, it pushes the plate on 

 one side into a groove situated between the inner plait 

 and the columella (pillar), where it is detained by the 

 pressure of the body of the animal, leaving the aper- 

 ture free, and when the animal withdraws itself, the 

 plate springs forward by the elasticity of its pedicle 

 and closes the aperture." (J. E. Gray, F.R.S., &c., in 

 Zoological Journal I. 212.) Of this singularly gifted 

 genus we possess three species, the Laminated Close 

 Shell (Clausilia laminata), about three-quarters of an 

 inch in length, very common on the trunks of trees, 

 on fences and among moss, in and near the park ; 

 the Rugose Close Shell (Clattsilia rugosa), half-an-inch 

 long, equally abundant with the last on walls, fences 

 and trees, among moss and under stones in the same 

 localities ; and " last, though not least," the rare 

 Clausilia Rolphii, which with us is nearly as plentiful 

 as either of the other two species, but more local and 

 less easily discovered. Not far from Uppark, within 

 the manorial boundaries, we have more than once or 



