241 
Relations and Differences . — •This cannot l)e confounded Avitli the 
preceding species, nor with any of its congeners, on account of its size, the 
hoat-like curve of its larger valve, and the great obliquity of its hinge line. 
Korizon and Localities . — A single specimen of this large and beautiful 
species was found in a brown micaceous sandstone at Branxton. 
Genus — PTEBINEA, A. Goldfass. 
Pterinea MACROPTERA, J. Morris.'^ 
PL XVI, Pig. 12. 
Rterinea macroptera , J. Morris, 1815, In Strzelecki’s Pliys. Descr. X. S. Wales and V. D. 
Land, p. 726, pi. 13, fig. 2, 3. 
,, ,, P. McCoy, 1817, Ann. Mag. Nat. Hist., XX, p. 299. 
,, ,, J. 13. Dana, 1849, Cfeol. Wilkes’ IT. S. Explor. Esped., p. 701. 
This is a moderate-sized, very oblique, inequivalved shell, rounded and 
largely-winged posteriorly. Its ventral margin is curved and sinuous towards 
its anterior part ; its beaks are rather thick, and very anterior, and in front of 
each beak is a prominent, rather long tootli nearly perpendicular to the 
hinge line. The hinge line is a little shorter than the shell itself, and 
posteriorly there is a very thin, long tooth, nearly parallel with the liinge 
line as in the Avicula. The right valve is rather smaller and more sinuous 
than the left. The anterior ear is short, and seems to have been pointed, if 
one may judge from the figure of it given by Mr. Morris. Probably the 
surface was nearly smooth, marked only with irregular rings of growth. I 
know only the internal cast of this species, unless, as I imagine, Cypri- 
cardia acutifrons, J. D. Eana, is identical with it. 
Dimensions. — The length of the hinge line is about 2*7 ^ centimetres, 
the mean breadth of the shell three and a half centimetres, and its greatest 
thickness close to the beaks from four to five millimetres. 
Relations and Differences. — This species differs from its congeners by 
the slight development of its hinge line, and the absence of surface orna- 
mentation. 
^ [This species has been made the type of a genus — Merismopieria. R. Etheridge, Junr., Geol. and Pal. 
Q’land.^, 1892, p. 271 ; Procs. Linn. Soc. N. S. Wales, 1889, IV (2), p. 204.— W.S.D.] 
" [The text gives 27 centimetres as the length of the hinge line, obviously a misprint. — T.W.E.D.] 
