144 



Lucina concinna, Huttou (Loripes), but the ornament and some 

 of the interior characters are different. 



Dimensions. — Antero-posterior diameter, 6 ; umbo-ventral 

 diameter, 55 ; sectional diameter of left valve, 1*75 milli- 

 metres. 



Locality. — Oyster beds of the River Murray Cliffs at ]N"or'- 

 West Bend. 



Lucina nuciformis, Tate. 



Reference.— -Trans. K. Soc, S. Aust., for 1885, t. xii., f. 10. 



Shell globose, very thick, regularly convex except in the post- 

 dorsal area, which is abruptly compressed. Surface ornamented 

 with subacute concentric ridges, broader than the intervening 

 sulci, and distant transverse threads more or less obsolete, 

 though usually conspicuous on the dorsal face of the concentric 

 folds. The concentric ridges are usually regularly disposed, 

 but in some individuals they are interrupted by from three to- 

 five broadish furrows, variable in width and relative position. 

 Margin of valves, except the hinge-line, strongly crenulated. 

 Lunule small, moderately impressed. 



Dimensions. — Antero-posterior diameter, 9 ; umbo-ventral 

 diameter, 9 ; sectional diameter, 8 millimetres. 



Locality. — Very abundant in the oyster beds of Blanche 

 Point, Aldinga Bay. 



L. nuciformis has a general resemblance to L. columbella, 

 Lamarck, but its nearest ally in recent creation is L. crassi- 

 lirata, Tate, inhabiting Southern Australia, from which it differs 

 by its greater gibbosity, more angulated behind, and thinner 

 lira?. 



Lucina araneosa, spec. nov. Plate xx., fig. 13. 



Shell quadrately orbicular, subinequilateral, thin, subven- 

 tricose ; umbones acute, approximate, incurved ; anterior side 

 slightly produced ; lunule moderately large, lanceolate, shallow. 

 Surface ornamented with distant concentric stria?, and incised 

 radial lines repeatedly dichotomous. 



Dimensions. — Antero-posterior diameter, 8 ; umbo-ventral 

 diameter, 7'5 ; sectional diameter of left valve, 2 millimetres. 



Locality. — Muddy Creek, lower beds. 



Lucina despectans, spec. nov. Plate xx., figs. 15 and 16. 



Shell quadrately ovate, subventricose, inequilateral ; umbones 

 post-median, acute, incurved, and approximate. Dorsal margin 

 slightly excavated in front, rapidly declining behind ; posterior 

 margin truncated ; ventral margin arched, rounded in front, 

 forming an obtuse angle where it joins the dorsal inflection. 



Surface ornamented with concentric stria? and depressed 

 subacute radiating ridges. 



