149 



the umbonal region and increase in number by bifurcation to- 

 wards tbe front, and numerous and close-set transverse lamella?. 

 The line of contact of tbe two valves is in one plane, and is 

 only slightly indented by ridges and sulci. 



Beak produced, sub-erect to slightly incurved, truncated by 

 a small foramen, and separated from the hinge line by a delti- 

 dium. Pores of the test circular few and large, as in W. 

 Garibaldiana, but not so numerous in the proportion of four to 

 five. Eeflected portion of loop unknown ; septum very promi- 

 nent, extending for about half the length of the valve. Crurse 

 very short ; loop towards its origin, rather broadly compressed, 

 and f alcately excavated on the upper side. 



Dimensions. — Length, "8 inch ; breadth, 6 inch ; depth, 5 

 inch. 



Observations. — In its sub-pentagonal form and small foramen 

 it closely resembles W. Garibaldiana, from which it is separable 

 by its inflated form, straight front margin, and by the bifurca- 

 tion of its strongly fimbriated ribs, and in certain details of 

 the loop. It comes nearer to W.flauescens than W. Garibal- 

 diana does, but, as with that shell, it has a much smaller 

 foramen and fewer and larger pores. 



Locality and Horizon. — Rather rare in the Polyzoal calci- 

 f erous sands forming the lower part of the sea-cliffs immediately 

 to the south of Port "Willunga jetty, Aldinga Bay, and at Sea- 

 ford, near mouth of the River Onkaparinga, St. Vincent's Gkilf ; 

 at Surveyor's Point, Torke's Peninsula. 



Waldheimia (?) divaricata, spec. nov.. Plate viii., figs. 8a— 86. 



This species has some resemblance to W. Garibaldiana,, but 

 is a narrower shell. The brachial valve is less inflated and 

 much depressed in front, and the convexity of this valve is more 

 or less interrupted by a median longitudinal depression, corres- 

 ponding to which in the other valve is a strong truncated keel. 

 The beak is more depressed, the deltidial area broader, and the 

 beak ridges more conspicuous. 



The ribs are en clievroa, rarely inconspicuous. It also 

 presents in form some agreement with Magasella Woodsiana, but 

 in that shell the valves are regularly convex, and the front 

 margin is not angulated. 



The loop is unknown, but there is a well-developed septum, 

 which extends for about half the length of the valve. There 

 are no signs of transverse attachments. 



Dimensions. — Length, 1 inch ; breadth, "75 inch ; depth, - 5 

 inch. 



Locality and Horizon. — In the red raggy limestones of the 

 River Murray cliffs at Mannum (many examples) . 



