548 NEW BRACIIIOPOnS PROM THK MIDDI.K PALAEOZOIC ROCKS, N.S.W., 



and its varieties, R. bouckardii. ami A', hai/ln (Brit. Foss. Bracb., iii., pp. 126- 

 128.). 



Obs. — The form liere described a^ees witb R. salteri Dav. in (i.) valves 

 equally convex; (ii.) small incurved beak; (iii.) medial radial ribs finer and at a 

 lower level tban tlie lateral ribs; (iv.) strong convexity of the valves; (y. ) bavins: 

 in the ventral valve a low narrow sinus extending from tlie beak to the front 

 margin; (vi.) valves ornamented with fine eimoentric lines; (vii.) having the 

 front margin slightly indented; (viii.) having the central ribs smaller and at a 

 lower level than the lateral ones. It differs from that species in the depressed 

 central area having fewer ribs and a smaller number of lateral ribs. With R. 

 bouchardii, it agrees in being almost as long as wide, and in the number and 

 character of the lateral ribs. It appears to differ from that species in having 

 only two depressed central ribs in the ventral valve and one in the dorsal valve. 

 The local specimen is smaller; this lias little significance when only a single speci- 

 men is available for comparison. Were I convinced that R. Imnchardii was 

 an established variety of 7?. salteri I would not hesitate to place our form with 

 that variety. Salter, Lindstrom, and de Koninck considered that 7?. boitchardii 

 and R. hai/Iei of Ilavidson were inseparable from R. salteri. 



de Koninck (Mem. Geol. Surv. N.S.W., Pal. G, p. 27) recorded the species 

 from Yarralumla, N.S.W., and gave an outline of Davidson's description of the 

 species, which he applied to the Yarralumla form ; he did not figure it. but stated 

 that it exactly agreed with Davidson's fig. 27a, PI. xii. Our fossil closely re- 

 sembles fig. 29 of the same ]ilate, that is, the varietal form R. houfhardii Dav. 



The specimens ilealt with by de Koninck were destroyed by fire in 18S2. Tlie 

 occurrence of the genus R.etzia in Australia adds another to the list of brachiopods 

 which have a world-wide distribution which, in the case of this gcmis. appears to 

 have been accomplished in a relatively sliort geological period . 



Ldc. and hnriznn. — The limestone bed of Tiimestone Creek, beneath the Lower 

 Trilobite Beds of Downing- Yass series. Parish of Derrengullen, County King. 

 Upper Silurian (= Wenlock) . 



This fossil was found associated with Farosites qnllilatidird Linn., /■'. Imiiallica 

 Gold.. F. multitahulata, Sphaere.rorhiis xiirus, Atri/pa reticularis Linn., .1. pulchrn 

 M. and Dun, etc. 



Family PRXTAMERIDAE. 



P> AKi.-ANDELLA iroLOKGEX.sis, u.sp. (Plate xxxi.. figs 0-11 . ) 



Spec. char. — Sliell sul)pentagounl to suliti-iaiigular. small, smooth, biconvex. 

 Pedicle valve strongly convex, es))ecially in the umbonal region, umbone promin- 

 ent, beak sluirt, depressed, gently incurved, but not overhanging the beak of the 

 brachial vahe; me<lial sinus wide and shallow (in some s]ieciuiens being hardly 

 visible, and in some, where it is more pronounced, there are traces of one or two 

 faint folds within it, and on the shells of young individuals neither sinus nor 

 opposing fold is pri^senl ) ; anteriorly mildly to moderately sinuating the brachial 

 valve. Brachial valve relatively small, moderately convex near the umbo, laterally 

 and anteriorly n\ore or less depressed, fold varies much in prominence, corre- 

 spciuding in this res]iect with the sulcus of the opposing valve in some individuals; 

 anteriorly its prominence is increased by the sliell surface on each side of it being 

 depressed (a feature coirniion to R. linpuifera Sow.), umbo moderately pro- 



