Shells of Common Occurrence. 151 



repose it inclines it at an angle of 70 . It derives 

 its generic name from a shelly bone attached to 



n 



& 58-59. 



57. Zua lubrica (the Common Varnished Shell), Muller. 

 58-59. Azeca tridens (the Glossy Trident Shell), Pulteney. 



the columellar teeth, and termed the clausium, from 

 closing up the aperture when the animal has 

 retired within its habitation. The next little group, 

 Zua lubrica (common varnished shell), and Ae2ca 

 tridens (glossy trident shell), are parallel in character, 

 only the Zua is toothless, the Azeca ovate and 

 toothed in the mouth. Both inhabit close shady 

 wood, moss, and under stones and decayed leaves. 

 The one is not quite, the other about, a quarter of 

 an inch in length. The next group comprises the 

 needle agate shell (Achatina acicula) y the shell of 

 the common amber snail (Succinea putris), and two 

 Physce or bubble shells (P. fontinalis and P. hyp* 

 norum) . The first is indeed minute, interesting, and 

 extremely delicate, having six convolutions, though 

 only a fifth of an inch in length ; but, indeed, dead 

 specimens found in old Saxon coffins are more 

 frequent than living ones occurring amongst roots 

 of grass and moss. Succinea is from succinum, 



