159 



sinuous. Peduncular valve slightly convex, with the heak hut 

 little produced, truncated by a slightly oblique foramen more 

 or less below the apex of the beak, excavated out of its sub- 

 stance, and completed by the two small deltidial plates and the 

 umbo of the brachial valve. Brachial valve almost flat, with 

 the slightest indication of a mesial sinus in the front ; hinge- 

 line a little arched. Surface of both valves ornamented with a 

 large number of fine radiating ribs, occasionally bifurcating, 

 and a few concentric lines of growth; margins ci'enulate." — 

 JStheridge. 



The founder of this species, being unacquainted with its 

 internal portions, placed it with a doubt in the genua 

 Terebrattdina, but having seen the loop, which offers no special 

 character, I can confidently refer it to that genus. 



The shell is conspicuous from its almost hemispherical shape ; 

 the peduncular valve being strongly convex and the brachial 

 valve flat, or with a slight medial depression. The ribs, which 

 are usually somewhat thick and crowded, are crenulated and 

 nodulated towards the front by strong lines of growth. The 

 edge of the valves is conspicuously crenulate. 



Dimensions of a large and narrow specimen — Length, '46 

 width, "35. One of the ordinary size gives — Length, - 35 ; width 

 *3 ; depth, "28 inch. 



Locality and Horizon. — This is one of the most widely diffused 

 of our palliobranchs, though not generally abundant. More 

 commonly the valves are widely gaping. 



In the Upper Murravian beds near Morgan on the River 

 Murray and cotemporaneous beds of Muddy Creek, near 

 Hamilton, Victoria (Tate). 



In the Lower Murravian at Mannum (Tate), and in the 

 coralline limestone at Mount Gambier ("Woods and Tate). 



In the glauconitic limestones, Aldinga Bay, and corres- 

 ponding beds at Surveyor's Point and Stansbury, Torke's 

 Peninsula (Tate). 



Terebratulina lenticularis, spec. nov. Plate vii., figs. 4a— c. 



Shell small, broadly oval, a very little longer than wide. 

 Brachial valve regularly convex deeper than the peduncular 

 valve, which is moderately convex and slightly impressed in 

 the middle line towards the front. Surface ornamented with 

 numerous rounded, bifurcating radial ribs, crowded towards 

 the front, and with imbricating concentric lines of growth 

 towards the same region. Beak stout, obtuse ; hinge line 

 narrow, slightly arched ; fissure large, deltidial pieces incon- 

 spicuous. 



Dimensions. — Length, *35 ; breadth, - 3 ; depth, *15 of aa 

 inch. 



