120 



form resembling a drop of water when it commences its 

 fall has given rise to its name. 



One of the minute productions of the Ancliff Lime- 

 stone. Two of the figures are magnified. 



NUCULA mucronata. 



TAB. CCCCLXXVL— ^g^. 4. 



Spec. Char. Subrhomboidal^ rounded, convex, 

 concentrically sulcated_, anteriorly mucronated. 



Two-thirds as long as wide, very minute ; the anterior 

 side is drawn out in the form of a flattened spine, and is 

 distinguished from the other portion of the shell by 

 being suddenly flatter. 



Found at Ancliff. The lower figures are enlarged. 



NUCULA angulata. 



TAB. CCCCLXXVL-/g^. 5. 



Spec. Char. Rhomboidal, concentrically striated ; 

 most convex near the beaks ; front rounded. 



Both sides of this shell are angular, and the lines from 

 their extremities to the beaks are nearly straight and 

 equal ; it is about half as wide again as it is long ; the 

 striae upon its surface are regular fine sulci, and not very 

 conspicuous. 



There are several similar species found in strata cor- 

 responding with the London Clay ; but all that I have 

 met with differ in form and the depth of their sulci. 



An uncommon Blackdown fossil. Magnified figures 

 are given below that of the natural size. 



