UNRECORDED GENERA OF THE OLDER TERTIARY FAUNA. 187 
angulation. Cartilage-pit linear with about seven teeth on each 
_ side. ; 
- Dimensions:—Antero-posterior diameter 11-25, anterior radius 
2:5, posterior radius 8:75 ; ventro-dorsal diameter 3°75. 
Locality:—Eocene, Gellibrand River. 
Externally Poroleda lanceolata is exceedingly like Leda Huttoni, 
but the anterior side is shorter and not so acuminate, the posterior 
hinge-line is straight not incurved, and the post-dorsal area not 
defined by a keel. It differs from P. elongata by its attenuate 
posterior side and by its straight hinge-line, which is sensibly 
divergent in that species; and though about half as large again 
yet offers the same proportionate dimensions. 
Family ARCID&. 
Genus Plagiarca, Conrad, 1875. 
This is in substitution for Macrodon, so that our species will be 
quoted as Plagiarca cainozoica, Tate. 
Genus Area. 
Subgenus Fossularca, Cossmann. 
Arca equidens, Tate, and Barbatia dissimilis, Tate, belong to 
the group typified by Arca quadrilatera, Lamk., on the authority 
of M. Cossmann, the author of the subgeneric name. 
Family UNGULINIDA. 
The generic name Scacchia should be expunged, the species 
erroneously referred to it belong to the group Felania of the genus 
Diplodonta = Mysia. 
Family ANATINIDA. 
Genus Pholadomya. 
PHOLADOMYA AUSTRALICA, spec. nov., Pl. xii., fig. 2. 
This is an important addition to our Eocene fauna, as though 
the species in the Older Tertiaries are few in number yet all the 
chief localities in Europe have a representative of the genus, the 
Oomaru formation in New Zealand contains P. neozelanica, 
Hutton. The present species occurs at Fyansford near Geelong, 
