140 



idea of this shell being a Liun&ean Patella. It is, how- 

 ever, a bivalve : the valves oblong, oval, flat, truncated 

 at the upper end, with a slight point in the centre, form- 

 ed by the angular depressed rib at the back, and giving 

 them the appearance of a duck's bill: the base of the 

 valves, which is inserted in the fleshy peduncle, is 

 pointed, and much narrower than the opposite patulous 

 termination. The animal protrudes on cither side of 

 its shell a long, but not articulated, fringed arm, which is 

 rolled within the shell in a spiral form, when contract- 

 ed. Lamarck only mentions one recent species of this 

 genus, but there are others known, though not yet 

 described, and also several fossil species. 

 Lingula anatina. 



HYALiEA. 



ANOMIA TRIDENTATA. I^lllTl 



Chemnitz 8, plate 108, Vign. 13, fig. F. G 



# 



This most extraordinary shell is of a thin transparent 

 horn-like substance, its form tricuspidated, with hollow 

 points, and finely striated transversely: the valves are 

 united, and, as it were, soldered together, but une- 



