135 



(Samarang Eccped?) ; St. Vincent Grulf, Guichen Bay, and 

 Portland, Southern Australia. 



Limopsis multiradiata, spec. nov. Plate xii., figs, la— 16. 



Shell ovate-orbicular, slightly inequivalve and oblique, thick, 

 convex ; umbones prominent, concentrically irregularly folded 

 and radially ribbed ; ribs thin, very numerous, narrower than 

 interspaces, bifurcating at about the middle ; cartilage pit 

 large, equilateral, three or four very small teeth under it, six or 

 seven larger ones on each side. 



Dimensions. — Length from umbo to the post-ventral margin, 

 9.5; greatest width, 10 ; thickness through both valves, 5 milli- 

 metres. 



Localities. — Glauconite argillaceous sands, Adelaide bore ; 

 and Turritella limestone bands, Blanche Point, Aldinga Bay. 



Among the Australian congeners this species resembles 

 L. aurita, somewhat in shape though less oblique, and the 

 undulating folds are thick and irregular. The conspicuous 

 radial ribs ally it to L. BelcJieri, which is distingui shed by a 

 peculiar style of tesselated sculpture produced by wavy concen- 

 tric fringes ; in L. multiradiata the radial ribs bifurcate, and 

 only in young shells is there present a fenestrated ornament 

 produced by the crossing of simple concentric threads. 



LIMARCA, gen. nov. 



Derivation from Lima and Area. Type, L. angustifrons, 

 spec. nov. 



Very inequilateral; cartilage pit lanceolate, excavated on the 

 hinge line, directed backwards ; hinge line with anterior den- 

 ticles and posterior elongated longitudinal teeth. No area 

 under the umbo. 



L. iniquidens, Sanberger, in Die Conchylien des Mainzer 

 Tertiarbeckens, 1863, p. 347, t. 29, fig. 5, is apparently con- 

 generic. 



The characters of the cardinal region recall Orenella in 

 Mytilidse, but the muscular impressions determine its place in 

 Arcadae, whilst its similitude to Limopsis is great. It agrees 

 with Trigonocodia in the absence of an area between the umbo 

 and the hinge line, and in this particular differs from Limopsis 

 and Cyrilla ; from Trigonocodia it differs by the fewness of the 

 cardinal teeth, the posterior of which are longitudinal and not 

 cross-set. 



Limarca angustifrons, sipec. nov. Plate viii., figs. 5a— 5b. 

 Shell small, subrhomboidal, convex, equivalve, very inequi- 

 lateral ; anterior margin regularly rounded ; posterior roundly 

 truncated ; ventral margin regularly convex outwardly. Sur- 



