The collections from Coverham (Albian) and Kaipara (about Maestrichtian) are dated from associated marine fossils. Those from Shag Point and Mikonui Stream are from coal measures conformably underlying Piripauan (upper Senonian) marine sediments and are probably themselves upper Senonian. The Pakawau coal measures have been correlated with those at Shag Point on the evidence of plant microfossils (R. A. Couper, pers. comm.).

The collections from Seymour River and Quail Flat (middle Clarence Valley) are from coal measures conformably underlying marine sediments containing Trigonia glyptica, T. meridiana (Woods, 1917) and fragments of a giant Inoceramus which is the zone fossil of the basal Raukumara Series as redefined by Wellman (1955). Wellman (1955) has correlated the base of the Raukumara Series with the base of the Senonian. The Seymour River coal measures are thus either basal Senonian or probably Turonian. They are here classed as ? Turonian.

The Paparoa Coal Measures have never been dated from satisfactory paleontological evidence and are variously classed as lower Cretaceous (?) (Wellman, 1950), possibly pre-Cretaceous (Cotton, 1951), probably upper Cretaceous (Gage, 1952) and lower Cretaceous (Couper, 1953).

The fossil cycads and ferns described below provide the following additional evidence for dating the rocks in which they occur:

The Seymour River coal measures contain leaves of Ptilophyllum and Pterophyllum, genera recorded in New Zealand from the Jurassic but not previously from the Cretaceous. Pterophyllum does not range above the Jurassic in other parts of the world (Seward, 1933: 332) and is apparently an archaic element in the New Zealand Cretaceous. Ptilophyllum ranges up to the middle Cretaceous in other countries (Seward, 1933, 413).

In New Zealand, Taeniopteris stipulata apparently replaced the Jurassic and Neocomian Taeniopteris spatulata during the Lower Cretaceous. No beds are known to contain both species. T. spatulata is present in the Styx River Series of Queensland, tentatively classed as Cenomanian by David and Browne (1950), but T. stipulata is unknown in Australia. If a change from T. spatulata to T. stipulata occurred at the same time in Australia and New Zealand, the Seymour River coal measures (which contain T. stipulata) are probably post-Cenomanian and may well be Turonian as suggested above.

Four species from the Paparoa Coal Measures are unknown in the upper Senonian of New Zealand, but range back to middle Cretaceous or older strata (Sphenopteris mackayi, Phyllopteris lanceolata, P. expansa, and Coniopteris ? lobata). On the other hand, the Paparoa Coal Measures lack the genera Pterophyllum and Ptilophyllum that persist into the Seymour River coal measures and contain more angiosperms than known pre-Senonian floras in New Zealand. They are thus probably older than upper Senonian but younger than Turonian, that is, lower or middle Senonian.

The Shag Point and Pakawau Coal Measures have been correlated from their plant microfossils (R. A. Couper, pers comm.). They seem to be younger than the Paparoa Coal Measures because they lack the older Mesozoic species of Phyllopteris, Coniopteris and Sphenopteris (mackayi) and contain three species of fern unknown in Paparoa or older beds.

As the Shag Point and Mikonui coal measures underlie Piripauan (upper Senonian), they and the Pakawau coal measures may be slightly older than the plants from Kaipara, collected from concretions containing ammonites probably of Maestrichtian age (Mason, 1953: 356). The Kaipara beds apparently lack the