NOTES ON A COLLECTION OF TERTIARY LIMESTONES 
Pecten praecursor, Chapman. 
(Plate VII., Figs. 1, 2.) 
P. consobrinus var. Tate, 1899, Trans. R. Soc., S.A., Vol. XXIII., 
p. 269. 
P. 'praecursor, Chapman, 1912, see present Memoir (No. 4), 
p. 36, pi. V., figs. 1, 2, 3. 
Perhaps the most abundant fossil remains in the Seal River 
polyzoal rock, with the exception of the polyzoa, are those of 
Pecten. Of this genus the species P. aldingensis is readily recog- 
nised, but the remaining specimens show a considerable diversity 
of ornament, partly due to the condition of the shells, so that it was 
somewhat difficult to settle their points of relationship. There 
are, however, several fairly well-preserved fragments which show 
that P. praecursor is present, and was an abundant form. One of 
the more perfect valves represented in the present series is nearly 
flat, and by the curvature of the ribs is seen to be a left valve. There 
are about ten or eleven primary folds with a strong median rib, on 
either side of which are one or two secondary ribs, and between 
these numerous riblets. Another specimen shows a part of the 
ventral margin of the valve, in which the surface ornament is par- 
ticularly well-preserved. The surface of the ribs is concentrically 
relieved by a series of imbricating lamelke similar to tlmt seen on 
well-preserved examples of P. antiaustralis.* The paucity of the 
ribs precludes any reference to that species, and, moreover, the 
intercostal spaces in our specimen are distinctly of a granular shagreen 
P. vraecursor is a characteristic fossil of the lower beds at Aldinga, 
as well as of many localities, chiefly (or all ?) Janjukian, m Victoria. 
Frequent in the polyzoal rock. Seal River. 
Lima bassi, T. Woods. 
(Plate VI., Fig. 9.) 
L. bassi, Tenison Woods, 1877, Proc. R. Soc., Tas.(Vol. for 1876), 
P ' L bassi, T. Woods, Tate, 1886, Trans. R. Soc., S.A., Vol. VIII., 
p. 24, pi. v., fig. 8;pl. viii., fig- 1. . 
An external mould of the shell occurs m the hard pink limestone. 
The ribs are rounded and transversely lamellated, and the inter- 
spaces also show fine and distinct transverse lamellae. The shefi 
is of the more elongate variety, common at lable Cape, and 
occasionally found also in the Balcombian-j 
* The specimens referred to by him, *n poJibly be referable to 
hom ttievariation ot ~ the 
s . Dun has already recorded Lima cf. bam from the King Island Tertiary lime- 
stone (foe. supra cit.). 
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