THE SHELL-LIMESTONE OF DURHAM. 



147 



B. ScHAUROTHiANA, Kivkhy. PI. IX., fig. 14; woodcut 10. 



B. Schaurothiana, Kirkby. " Ann. Nat. His.," 3rd 

 ser., vol. ii., p. 329, pi. X., fig. 14. 

 Length, l-18tli of an inch ; height, l-40th of an inch. 

 Carapace sub-hexagonal, rather ventricose dorsally; dor- 

 sal margin straight centrally ; antero-dorsal region con- 

 vex, sloping gradually to below one-third of height ; 

 postero-dorsal region very abrupt, descending two-thirds 

 of height in a right line ; ventral margin straight, rising 

 abruptly to meet dorsal margin posterior, and very con- 

 vex anteriorly ; anterior extremity convex, projecting most 

 in dorsal half; posterior extremity angulate, the postero- 

 dorsal region and ventral margin forming almost a right 

 angle ; lateral contour almost lenticular, the greatest 

 diameter being rather posteriorly situate; liinge^ strong; 

 flange of left ventral margin small, sub-central. 



