* Trochus Josephi, 7’. Wds. 
Se * Gibbula equisulcata, 7’. Wds. 
136 
!* Ringicula lactea, Johnst. 
!* Cylichna Woodsii, ate 
“«  Clarkei, 7. Was. + sp. 
es “« erassigranosa, 7’. Weds. : Volvulella sp. 
(part, junior) ! Atys sp. 
* Calliostoma atoma, Johnst. ae 
+ ss Tasmanica, Johnst. : ; : 
x cs Blaxlandi. Johnee Aturia australis, McCoy 
* es latecarina, Pritch. 
!* Cantharidus alternatus, T. Was. a 
(Thalotia) Carcharodon angustidens, Aq. 
!* Euchelus Woodsii, Johnst. Oxyrhina trigonodon, Ag. 
!* Margarita Keckwicki, 7. Wds. Lamna elegans, Ay. 
Fissurellidza malleata, Tate ! Mylobates plicatilis, Davis 
!* Emarginula transenna, 7’. Wds. 
MAMMALIA. 
* Tugalia crassireticulata, Pritch. | 
Haliotis ovinoides, McCoy (fide | !* Zeuglodon brevicuspidatus, V'ate 
Pritchard) Diprotodontoid marsupial (Ho- 
! Acton scrobiculatus, 7. Wds. bart Mus. !) 
CHAPTER III. 
GENERAL REMARKS—HorRIZONS OF THE EOCENE. 
Regarding the main divisions of the Tertiary deposits of 
Southern Australia into Eocene, Miocene, and Pliocene there is 
little difficulty, the paleontological being confirmed by the 
stratigraphical evidence. The two latter groups are of compara- 
tively limited development in the province, but the first named, 
besides being spread over a wide area, shows such variation in the 
faunal contents of the beds as to render their correlation no easy 
task. In our previous papers we have treated the Eocenes as a 
whole, without attempting further subdivision, the simple reason 
being that no satisfactory basis of classification presented itself. 
That the beds in question are of Eocene age was discussed fully 
in Part I., and it may be added here that on this point there is 
unanimity among all observers who have given adequate atten- 
tion to the subject. The chief argument relied on is the’ propor- 
tion of recent molluscan species, which nowhere exceeds 31 per 
cent. As a fact the percentage is usually under 2, the only ex- 
ception being in the Table Cape section with a record of from 2.2 
to 3 per cent. of living species, so that a margin is left for what 
further researches may possibly disclose. In some beds the per- 
centage is less than 1, and in others between 1 and 2, but it 
would be extremely unwise, as well as contrary to the practice of 
geologists, to form conclusions as to relative age on such minor 
variations as these, since they may depend upon the number of 
species collected, or upon other causes which need not be cited. 
As a convenient, though admittedly rough, means of classifying 
Tertiary strata, the percentage system may serve for distinguish- 
ing their broad divisions, but must necessarily fail when applied 
to the discrimination of minor zones a deposition, where the re- 
corded variation does not exceed 1 or 2 per cent. 
