DESCRIPTIONS OF THE SPECIES OF LIMA. 235 



ter prove to be a variety of the same, but a specimen of it, 

 the same valve and the same size as my fossil, kindly lent me 

 by Mr. G. B. Sowerby for comparison, presented the follow- 

 ing differences. Posterior opening, wider and shorter, conse- 

 quently the slope not so great nor the opening so long as in 

 the recent shell, which is also more oblique, rather deeper, 

 and the ligamental area not so large as in the fossil, and the 

 stria are finer and more regular in the recent shell, nor does 

 our shell deserve the name of tenera or fragilis, (the name 

 given to it by Dr. Fleming), as it is thick and strong. 



I presume it is rare in the crag, not having found the op- 

 posite valve. 



3. Limafragilis, Auct. PI. 3, fig. 3. 



Pecten fragilis ; Montague, 'Test. Brit.' p. 63, Supplement. 



Localities: Coralline crag, Sutton. 



Red crag, Walton, Essex. 



The copious description given by Col. Montague leaves 

 nothing to be added. Our shell appears rather thicker and 

 firmer, with a very slight difference in the stria. 



By no means rare at Sutton ; rather more so in the red crag, 

 owing probably to its fragility. 



4. Lima plicatula, Nobis. PI. 3, fig. 4. 



Shell inequilateral, oblique, convex, ovato-orbicular, anterior truncated, 

 costated, costm 14-16, ligamental area small, oblique, lunula transversely 

 crenulated. Length -^ of an inch. 



Locality : Coralline crag, Sutton. 



A small shell and rare ; my specimens not more than ■£? of 

 an inch in length. The ribs are elevated, and as broad as 

 the spaces between them, which are strongly imbricated; 

 the ribs showing slight indentations ; (a) is an enlarged fi- 

 gure with a portion more highly magnified. One ear on the 

 posterior side is large and projecting while the other is scarce- 

 ly visible ; it differs from Lima plicata of Deshayes, inasmuch 

 as it is smaller and more orbicular. The central liganlental 

 area is very small and oblique, sloping towards the posterior 

 side, which is not given in the figure. 



Sub-genus Limatvla. 



1. L. Limatula ovata, Nobis. PI. 3, fig. 5. 



Shell equilateral, ovate, convex, equivalved, closed ? bivalve ; ligamental 

 area large ; umbones distant, costated, costce 6-8, edge crenulated. — 

 Length ^ of an inch, breadth jf , depth of single valve ^. 



