PREFACE. 
The two following plates illustrate the curious, extinct Marsupial 
genus Procoptodon ; differing from the true Kangaroos in the much 
more complex teeth; and in haying the front molar formed for 
grinding. The more massive lower jaws being joined by bony union 
in front, and the tusks inclining upwards, showing a relation to the 
huge extinet Diprotodons of the same Pliocene Tertiary deposits. 
The fourth plate shows the extraordinary repetition in Australia 
of the curious occurrence in the Crag of Suffolk of a multitude of 
ear-bones of Whales : three species of which are here shown, in beds 
of nearly the same age, by very similar Cefotolites, as these fossils 
are generally termed. 
The fifth plate makes known the teeth of a gigantic fossil extinct 
species of Spermaceti Whale from the Older Pliocene beds of Mor- 
dialloc. It also represents one of the simple, conical, anterior teeth 
of the Miocene Tertiary extinct genus of Whales, Squalodon, from 
the Miocene Tertiary beds of Waurn Ponds, near Geelong, discovered 
by Mr. Nelson of that place, who enabled me thus to add to our 
previous illustration of the lobed, posterior teeth of Squalodon Wil- 
kinsoni (McCoy), figured in our second Decade. 
The sixth and seventh plates give some further important fossil 
Mollusea, characteristic of the Upper Silurian formations, from 
Gippsland. 
The eighth plate gives figures of a new and abundant species of 
Hinnites, very characteristic of the Victorian Miocene Tertiary 
deposits. 
And the two last plates represent some of the more interesting 
and widely distributed of our Tertiary Sea Urchins. 
The four remaining Decades required to complete the work will 
continue the illustration of the fossil collections made in the course 
of the Geological Survey of the colony. 
Freprerick McCoy. 
2nd December 1878. 
