65 



TEREBRATULA triquetra. 

 TAB. CCCCXLV-^^. 1. 

 Spec. Char. Suborbicular with a produced, 

 incurved beak ; valves equally convex ; 

 front slightly indented ; beak obtusely keel- 

 shaped ; with carina on each side. 



X HE length and breadth of the upper valve are equal ; 

 the edge is level and sharp, and not much thickened by 

 age ; the indentation in the front produces a slight con- 

 cavity of the surface, that extends more or less from the 

 edges, interrupting the regular convexity of both valves ; 

 the larger valve is besides obtusely keelshaped near the 

 beak, which has also a sharp ridge upon each side of it, 

 whence the perforation is triangular ; the surface is re- 

 markably smooth. 



Found at Felmarsham by Miss Ludlow. 



TEREB RATULA indentata. 

 TAB. CCCCXIuY. —Jig. 2. 



Spec. Char. Elliptical, smooth, more or less 

 gibbose ; valves equally convex ; front 

 deeply notched ; beak small, much incurved . 



-I- N the young state this Terebratula, like many others, 

 shews but slight signs of the marginal notch ; when full 

 grown the notch is deep and obtuse-angular ; broad 

 furrows extend from it about one third the length into 

 each valve ; its length is nearly twice its width. 



Found abundantly in a dark greenish grey limestone 

 at Banbury, and several other places. Tlie two sides 

 are not always equal. 



TEREBRATULA Sacculus. 

 TAB. CCCCXLVL— ;%^. 1. 



Spec. Char. Obovate, gibbose, with a deep 

 channel along the larger valve; front in- 

 dented. 



Syn. Conchiliolites Anomites Sacculus. Mar- 

 tin Pet. JDei'h. tab. 46yjigs. 1 and 2. 



A. SMALL almost globose shell, well distinguished by the 

 broad and deep furrow, that divides the larger valve into 

 two lobes ; the other valve has also, near its edge, acon- 



