UNRECORDED GENERA OF THE OLDER TERTIARY FAUNA. 169 
beds,” in which the species have been greatly reduced in number, 
and to estuarine or fluviatile beds with plant-remains only. This 
discovery is of the highest interest, as hitherto no marsupial 
remains are known older than the age of the Diprotodon or Plio- 
cene ; and leads us to hope that other progenitors of the modern 
Marsupialia of this Continent may yet be found, and so help to 
solve the question of their geographic origin. Professor Spencer 
has promised to investigate the fossil with the view to determine 
the classifactory position of the oldest known Australian marsupial. 
Class PIsces. 
Genus Strophodus. 
S. Eocenicus, sp. nov., Pl. xii, fig. 6. 
I am not aware if representatives of this genus have been 
signalled in rocks younger than Upper Cretaceous, yet I have no 
hesitation in referring to it some fish-plates, which are not of 
uncommon occurrence at Cheltenham, Port Philip Bay, and also 
have been found by mein the Lower Murravian, and by Mr. 
Sweet from the limestones of the Moorabool River. The species 
is somewhat comparable with S. magnus, Agassiz, but is narrower 
with coarser reticulate rugosities and the inner margin is very 
finely reticulate-punctate ; the outline is subtrapezoidal, about 
three times as long as wide, broader at one end, which is con- 
vexedly truncate and narrower at the other which is truncated; 
uniformly depressedly-convex above. Length 30 mm., width 8, 
increasing to 11 mm., thickness 7 mm. 
Genus Otodus. 
This genus is now merged in Lamna. 
Genus ? of Chimeride. 
Dental plates belonging toa Chimeroid fish have been collected 
at Grange Burn, Hamilton, by Mr. Sweet, but the material avail- 
able is not sufficiently complete to permit of generic determination. 
Class CEPHALOPODA. 
Genus Spirulirostra. 
