ever, this is apparently a distinct keeling, not a truncation, 

 the shell being bent inwards almost at right angles, whereas 

 in Burriera the shell itself is not infolded, but abruptly 

 cut off, so that the surface of the interior forms an even 

 angle with that of the truncation. The ornamentation in 

 these Silurian genera also, is radial not concentric. 



From a stratigraphical point of view, the discovery of 

 one of the Lunulicardiidae in Australia is of no less interest. 

 Previously the family had not been found in strata newer 

 than the Devonian, therefore its range must now be extended 

 from the Silurian to the Permo-Carboniferous. As to be 

 expected in the wide interval bridging the Devonian from 

 the Permo-Carboniferous, considerable evolution had taken 

 place in the group, and Burriera, which was so far the last 

 survivor, was really an extreme of evolution, and differed 

 considerably from what were probably its ancestors. 

 Burriera Dunii, sp. nov. 



Specific Characters.— Test triangular, anteriorly elon- 

 gated, and acuminate. Posteriorly rounded. Both valves 

 nearly flat, with a well marked anterior gape. Test gradu- 

 ally thickening towards the acute anterior termination, 



sharply truncate and straight, the truncate surface being 



at right angles to that of the valve. This at first sight 

 suggests that the shell has been broken. The posterior 

 adductor impression is prominent, and equal in diameter to 

 nearly one third of the height of the shell. It is rounded 

 on its lower and inner edges, and slightly ridged upon its 

 ventral margin. The cast of this impression shows right 

 thin, parallel, curved ridges (striations upon the test) 



distinguishable. The pallial line is simple and straight, 

 and above it and running parallel to it, is another faint lineal 



