101 



right valve ; faintly rayed and concentrically laminated. 

 Interior of botli valves with conspicnous radial riblets within 

 "the pallial line and terminating there ; the denticulations of 

 the cardinal ridges continniug on the lateral margins and 

 .gradually developing into riblets. 



Dimensions. — Length, 60 ; height, 7'o millimetres. 



Localities. — Turritella clays and glauconite limestones, 

 Aldinga ; glauconite sands, Adelaide bore ; chalk-rock. Bunda 

 •Cliffs of the Great Bight. 



D. sigillata differs from D. dissimilis in the erect front of 

 i;he attached valve and finer ornament, and by the radial 

 riblets within the pallial line ; in the last particular this 

 ■species recalls certain Plicatida of the Cretaceous and Jurassic 

 rocks of Europe. D. sigillata approaches externally rather to 

 Ostrea than to Plicatida, whilst the converse is true of its 

 •congener, D. dissi?nilis. 



FAMILY ANOMIID.E. 



Anemia cymbula, spec. nov. Plate ix., fig. 5. 



Shell obliquely oblong- ovate, somewhat solid, convex, with 



compressed sides ; umbo subcentral, acute, perceptibly 



elevated, submarginal ; surface densely rayed with slender 



riblets, which are covered with subspinous transverse scales. 



Dimensions. — Height, 10 ; length, 5 ; depth of valve, 3 5 

 .(nearly) millimetres. 



Locality. — Turritella-clays at Blanche Point, Aldinga Bay. 



GrENFS PLACUXA:^OMrA. 

 SYNOPSIS OF SPECIES. 



Valves ornamented with coarse radial threads, subspinose. 



P. lone. 

 Valves ornamented with fine radial threads. P. sella. 



Placunanomia lone, Gray. PL v., figs. 7a— 7b. 

 References. — Proceedings Zoological Societ}^, 1810, p. 123 ; 

 Hutton, in Cat. Marine Moll, of X.Z., 1S73, p. 81. 



Superior or left valve irregularly orbicular, usually slightly 

 <convex, but varying from flat to very convex, horny-pellucid, 

 surface ornamented with imbricating scaly lamella; and radial 

 i}hreads or ridges ; umbo sub-marginal, depressed, with a 

 slight back curvature. Ligamental scar within the umbonal 

 cavity transverse oblong, circumscribed by a raised border, 

 radially striated, adjacent to the anterior margin of which is a 

 small conspicuous pedal scar. 



Dimensions. — Length, 54 ; height, 17 millimetres. 

 Localities. — Oyster banks of the Upper Murravian at the 

 JS'orth-'West Bend, and of the Upper Aldinga series at Aldinga 



