76 POPULAR BRITISH CONCHOLOGY. 



L. leucoma (known as laded) : smaller, without sculpture ; 

 ligament internal. 



L. fiexuosa : small, white, with folds at the sides. 



L. divaricata : still smaller, with strise meeting at the centre, 

 and diverging towards the sides of the shell. 



L, ferniginosa : minute, brown, heart-shaped. 



II. DiPLODONTA rotundata is the only remaining British 

 mollusc of this group. It burrows in sand on our 

 southern shores, thence ranging to the Mediterranean. 

 The foot is pearly white, rather flat, and neither sipho- 

 nal tubes nor orifice could be found by Mr. Clark, who 

 examined it very carefully. The shell is very like a 

 Lucina, of a round shape, smooth, with a broad, shining, 

 uusinuated pallial impression. 



