Upper Cambrian Limestone, 111 



Leperditia cajjsella, sp. nov. (Plate IX., Figs. 4«, b). 



Description. — Carapace seen from the side, broadly ovate, oblique. 

 .Hinge-line straight and thickened; about tAvo-thirds the length of 

 the carapace, anttrior border almost at right angles to the back, with 

 .a slight re-entrant curve, obliquely rounded to the widely curved 

 ventral edge; posterior extremity subangularly rounded and 

 obliquely produced. Sides of carapace coimpressed, especially 

 anteriorly and dorsally; highest part in the posterior third. Sur- 

 face of valves finely punctate and crossed with fine linear markings 

 parallel with the dorsal border. Muscle spot sub-central and slightly 

 •depressed, from which radiate fine striae. There is a well marked 

 ,-sub-median pit a litle below the thickened hinge-line. End view, 

 .acuminately ovate. 



Dimensions. — Holotype ; length, 3.9 mm.; greatest height, 3.05 

 :mm. ; thickness of carapace, 2 mm. 



Observations. — The present species, Leperditia capsella^ has many 

 points of resemblance to L. canadensis, Rupert Jones, ^ another of 

 •the species found in the Calciferous Sandstone of Canada, and 

 presumably of Upper Cambrian age. The more compressed form of 

 the carapace, higher valves and stronger re-entrant curve of the 

 lanterior border, serving to distinguish our species, the outline of 

 which reminds one of a seed-capside of the common English weed, 

 the Shepherd's Purse (Cap.^eUa hnrsa-pa.storis). 



Occurrence. — One specimen, left valve (Holotype), from the Sweet 

 "Collection ;2 also a right valve, Tate collection, S. Australian 

 Museum, lent by Mr. W. Howchin. From the grey limestone of 

 *Curramulka, S. Australia. 



Genus Isochilina, Jones. 



Isochilina sweeti, sp. nov. (Plate IX., Figs. 5«, b). 



Descrijjtion. — Carapace large, solid, strongly convex, highest 

 ,:about the centre. Seen from the side the valves are sub-circular, 

 ■slightly oblique. Hinge-line straight, of moderate length, rather 

 more than half the long diameter. Anterior border nearly at right 

 i^angles to the hinge-line, rounded obliquely below to meet the widely- 

 "Curved ventral border. Posterior extremity produced and well- 

 rounded. Edges of valve bordered by a fairly wide flange, rounded 



1 Aim. Miiu. Nat. Hist;, str. S, vol. i., "1858, p. 244, pi. i\., flRs. IMf.. 



2 Presented to the National Museiiiu. 



