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[Read before the Wellington Philosophical Society, 27th August, 1924; received by Editor. 28th August, 1924; issued separately, 6th March, 1926.]
The following notes are based on some specimens collected by Dr. P. Marshall, who kindly handed them to me for examination. They all come from Bull's Point and Batley, Kaipara Harbour, New Zealand, and the geology of the district has been fully dealt with by Dr. Marshall himself.
Though the plants do not give any indication of their exact horizon, they are associated with ammonites which point fairly definitely to an Upper Senonian (Campanian) age. * Most of the plants so far discovered are either fragmentary or belong to form-genera which are of little use for correlation purposes; they are, however, of considerable interest botanically, more especially as there are some petrifactions as well as impressions.
They occur mainly in hard nodules with an irregular fracture, from which it is difficult to obtain complete specimens; and, moreover, the plants were evidently in a fragmentary condition before fossilization. The impressions are partially petrified; thus, in the case of the fern Taeniopteris batleyensis, sections reveal to some extent the structure of the midrib, while collodion imprints of some of the leaf-fragments show the outlines of the epidermal cells. The araucarian leaves show the rows of stomatal pits very clearly, and can also sometimes be sectioned fairly successfully, while some of the araucarian wood is very well preserved.
One of the nodules is of great interest, for it consists largely of petrified vegetable debris in a sandstone matrix, and at once suggests comparison with plants containing nodules from other places. In its general structure this nodule closely resembles those from Upper Cretaceous beds of Japan described by Dr. M. C. Stopes (1909), from which a large and interesting flora was obtained (Stopes and Fujii, 1910). The matrix of the Kaipara nodule (kindly examined for me by Mr. W. Campbell Smith) consists of very angular quartz-grains in a calcareous cement together with a few crystals of feldspar, traces of mica, some green flakes of chlorite, and a very few grains which might be glauconitic. All these constituents are probably of detrital origin. Scattered through the matrix are abundant petrified plant-fragments and a few Foraminifera and other shells. Sections of other nodules showed a very similar mineral structure (sometimes more finely grained), but with very little plant-debris except for highly comminuted tissue-fragments. The Japanese nodules also vary in the amount of the plant contents, some containing only shells and no plants, while only a few have the fragments thickly massed. The Kaipara nodule differs from the Japanese in being slightly coarser-grained, with rather more quartz, while the plant-remains are not so well preserved. Dr. Stopes gives a detailed
[Footnote] * The collections of ammonites include the well-known form Pseudophyllites indra and the local representative of Gaudryceras kayei; also species of Puzosia, a form close to Acanthoceras rotomagense, and a form close to Phylloceras velledae. It appears, therefore, that if a single horizon is represented it must be somewhat lower than the Campanian. The question is discussed in a paper on “Upper Cretaceous Ammonites” in this volume.—P. Marshall.
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Fig. 1.—Taeniopteris batleyensis n. sp.
Fig. 2.—Taeniopteris batleyensis n. sp. The sori are very worn, and their structure is doubtful.
Fig. 3.—Fern-petiole from stem of Dadoxylon. Diagrammatic view of transverse section.
Fig. 4.—Sphenopteris sp.
Fig. 5.—Araucarites marshalli n. sp. Leaves attached to axis.
Figs. 6, 7.—Araucarites marshalli n. sp. Single leaf.
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Fig. 8.—Araucarites marshalli n. sp. Small portion enlarged to show rows of stomatal pits.
Fig. 9.—? Dammarites sp.
Fig. 10.—Carpolithus zeelandica n. sp.
Fig. 11.—Dadoxylon kaiparaense n. sp. Part of transverse section magnified, showing a fairly well marked annual ring, which, however, was not visible to the naked eye.
Fig. 12.—Dadoxylon kaiparaense n. sp. Radial section.
Fig. 13.—Dadoxylon kaiparaense n. sp. Tangential section.
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comparison of her nodules with the coal-balls and roof-nodules of the English Carboniferous beds. The resemblance is greater to the latter—which, however, are much finer grained, and contain very little quartz, while the plant-fragments are never closely packed. The differences are due to differences in deposition: the plants in the roof-nodules had drifted and been sorted out, but “the numerous minute fragments of the Japanese nodules … could neither have drifted far nor long before they were covered and preserved in that potent preservative and petrifying solution, sea-water” (Stopes, 1909, p. 203). The granular Kaipara nodules with their marine animals were also obviously formed fairly near the shore where detrital matter was accumulating, but the plants had perhaps drifted a little farther, for they had decomposed more than the Japanese plants, so that only pieces of wood and the thicker and more resistant leaves have been at all well preserved. There are at Kaipara a few fairly large stem-fragments (see below), but in the nodule which has been particularly noticed here there are only small scraps of coniferous and dicotyledonous wood, fragments of bark and leaves, and some rather poorly preserved seeds, none of which can be identified definitely. It is possible, of course, that other nodules may be obtainable which, though of unpromising appearance, may contain recognizable petrified plant-remains.
The English roof-nodules are found in the beds immediately above coal-seams, while the Japanese nodules occur at least 100 ft. below the seams in their neighbourhood; but the association with coal-seams is probably-more or less accidental, and the floras of the coal and of the nodules are not necessarily identical. They might, indeed, as Dr. Stopes believes is the case with the roof-nodules, belong to different plant associations, a fact which must be borne in mind when questions of correlation arise.
The recognizable plants from Kaipara are few in number. As in the Japanese nodules, and as in Upper Cretaceous floras generally, there is a mixture of ferns, gymnosperms and dicotyledons, but the material is insufficient for comparison with any other fossil flora. In the case of New Zealand no Upper Cretaceous flora has yet been adequately described, for the early work of Hector and Ettingshausen consists largely of nomina nuda, and Arber's monograph extended only to the Lower Cretaceous.
The following plants are recorded here: Ferns—Taeniopteris batleyensis n. sp., Sphenopteris sp. Gymnosperms—Araucarites marshalli n. sp., Dadoxylon kaiparaense n. sp., Carpolithus zeelandica n. sp., ? Dammarites sp. Dicotyledons—Phyllites sp., dicotyledonous wood.