123 



This species has a general resemblance to P. Zecdandica., 

 G-ray, from which it differs by the longitudinal scaly ribs being- 

 confined to the dorsal surface, and by its much greater con- 

 vexity. 



Pinna, s'p. indet. 



Apical portions only known. Valves acutely angulated, 

 with faint longitudinal ribs separated by broad interspaces on 

 the ventral slope, crossed by undulose ridojes. 



Calciferous sandrock, Eiver Murray cliffs, near Morgan. 



FAMILY MYTILID.E. 

 GrENUS MODIOLA.. 



Shell ovate-oblong, inflated. M AdeJaidensis, 



Shell elongated, inflated. II. sp. 



Shell elongated, compressed. 3f. sp^ 



Modiola Adelaidensis, s^jpec. nov. PI. xi., fig 3. 



Ovate-oblong, with inflated subterminal beaks, the anterior 

 end very narrow and obtuse ; the post-dorsal portion is dilated 

 and becomes gradually flattened, the ventral side is compara- 

 tively narrow and convex. Posterior margin broadly sub- 

 rotund, dorsal margin slightly curved, ventral margin straight, 

 anterior margin rounded, projecting beyond the umbo. Surface 

 with well-defined concentric folds of growth. 



Diviensions. — Greatest length, 28 ; greatest width at right 

 angles to longitudinal diameter, 18 ; greatest thickness through 

 both valves, 13 millimetres. 



Locality. — Glauconitic sands, Adelaide bore. 



This fossil species has some resemblance to certain individual 

 varieties of the recent M.flavida, but is distinguished by the- 

 larger and less anterior umbones. 



Modiola, sp. indet. 



Similar to the last, but longer and narrower ; the single- 

 specimen known is nnfortunately somewhat crushed. 

 Length, 43 ; breadth, 17 millimetres. 

 Locality. — Glauconite sands, Adelaide bore. 



Modiola, sp. indet. 



A compressed elongate shell, with nearly terminal beaks, is- 

 indicated by casts in the calciferous rocks on the Eiver 

 Murray, and at Salem, near Callington, on the Eiver Bremer. 



Length, 55 ; breadth, 20 ; thickness through both valves, 13^ 

 millimetres. 



