153 



Cardium hemimeris, spec. nov. Plate xiv., figs. 2a — 2c. 



Shell thin, quadrately-oval, subglobose, inflated ; umbones 

 ■elevated, incurved, submedian ; dorsal margin slightly arched; 

 posterior margin truncated, a little incurved towards the lower 

 rounded angle ; posterior area flattened, very steep. The 

 anterior half of the surface of the valve is ornamented by 

 numerous regular, equal, flat riblets, crossed by finer and 

 closer concentric threads, which are somewhat irregularly dis- 

 posed, being here and there somewhat undulose and confluent ;* 

 the intersection of the riblets and the lira? produce a tessel- 

 lated ornament. The posterior half is ornamented with about 

 50 flat, narrow riblets, closely beset with small tubular, conical 

 spines. Margin of the valves strongly toothed. 



Dimensions. — Antero-posterior diameter, 13 ; umbo-ventral 

 diameter, li ; sectional diameter of both valves, 10 milli- 

 metres. 



Localities. — Very common in the clayey green sands, Ade- 

 laide bore ; rather rare and of small size in the older beds at 

 Muddy Creek ; in a deep well-sinking, Cooke's Plains, east of 

 Wellington, Eiver Murray. 



FAMILY UNIONID^. 



The generic references to the following species were made 

 by the original describer purely on external resemblance, which 

 is of no value. As Anodonta is not actually known either re- 

 cent or fossil in Australia, and JJnio is, it will be more con- 

 sistent therefore to place all our fossil TTnionidse, so long as 

 the hinge characters are unascertained, in the latter genus. 



Unio Tamarensis, R. Etheridge, jun. 



Reference. — Anodonta Tamarensis, Eth., Eoy. Soc, Tasm., for 

 1880, p. 22, figs. 3-4. 



Older Tertiary beds of the Tamar Eiver, Launceston, on the 

 authority of Mr. E. M. Johnston. 



Transversely elongate, about twice as long as broad ; pos- 

 teriorly acuminated, anterior side very short, convex, and very 

 gibbous ; length, nearly four inches. 



Unio Johnstoni, R. Etheridge, jun. 



Reference. — Op. cit., p. 20, figs. 1, 2. 

 Same locality as the last. 



Obliquely oval, compressed ; breadth, about one-third less 

 :iban the length, which is three and a-half inches. 



The fig. 2b incorrectly represents the concentric sculpture. 



