536 Transactions. 
older than the Chatton sands; and at Pomahaka, not far above the 
coal-measures, are tuffs containing a very peculiar and apparently brackish- 
water fauna of about a dozen species, which give no indications of their 
. geological age. Apart from these occurrences, Lower Tertiary beds have 
not been discovered in Southland; no trace has yet been found of the 
put forward prove correct, it is evident that a rich molluscan fauna already 
flourished in New Zealand before the Awamoan, and, if one may judge by 
generic similarities, evidently gave rise to the Awamoan faunas. The 
equally rich. 
There is still, however, the tantalizing stretch of limestone even at 
' Clifden, during whose deposition much faunal change must have occurred. 
From the thickness of the Clifden section it is evident that the deposition 
of the Ototaran-Hutchinsonian in the Oamaru district must have occupied 
a very long period of time. ark gives the maximum thickness of 
bands 2-6 oceupy another 100 ft., and band 7 is 175 ft. thick. Now, the 
evolutionary differences shown between successive bands of the fossiliferous 
s seem to be quite as great as, for instance, between the Hutchinsonian 
and basal Awamoan, or Awamoan and Mokauian, so that, the rates of 
evolution being assumed equal, either these stages represented quite short 
time-periods, or the Ototaran-Hutchinsonian period, as at present under- 
stood, was of considerable duration. 
The unfossiliferous nature of the Oamaru stone has been the source of 
much palaeontological confusion as regards faunas above and below it, 
and has prevented the clear reading of the evolutionary sequence between 
our early and middle Tertiary faunas. Although the upper beds at Clifden 
will materially help in this respect, the thick basal limestone again prevents 
the complete solution of the problem, and at present we are still left with 
the apparently sudden appearance above the limestone of a rich and varied 
auna, which in some respects is very like, and in others very unlike, that 
found in pre-Ototaran beds. It can only be said here that a careful com- 
parison of material from Wharekuri, Clifden, and Otiake leaves the impres- 
sion that the evolution of our fauna proceeded equably throughout the 
limestone regime, an that if a new fauna did enter by means of a shallow- 
water connection at that period it scarcely disturbed the hardy pioneers 
al ау in possession. 
. The arrival of a new fauna is generally su d to i i 
е ма OLG г Tau : pposed to imply increased 
саза, ar oe resulting in extinction of all but the enr аА members 
pis Spear in gers The weaker members of the invading troop would 
al ai i та the changed conditions unfavourable, and would probably 
be h. ара may possibly account for the failure of a large number of 
eae ipo pues — sad genera to survive beyond the 
wamoan: e.g., Рона. aeuticingulata (Suter), Merica brevirostris (Hutt.), 
Hinnites trailli Hutt., Erato neozelanica Suter, &c. At the susie vat 
