C. T. Treeh rnonu — Age of the Maitai Series. 53 



EXPLANATION OF PLATE III. 



(All figures x 12 diams.) 



Fig. 1. Membranipora crateroides. Zone of B. mucronata. Wey bourne, 



i, 2. ,, ,, ,, ,, Norwich. 



,, . 3. Membraniporella tceniata. East Dean, Hants. 



,,4. ,, ,, Shawford, Hants. 



,. 5, 6. ,, bitubularis. Seaford. [Green, Kent. 



., 7. Cribrilina tumuliformis. Zone of M. cor-anguinum. Leaves 



,,8. ,, ,, ,, ,, Gravesend. 



,,9. ,, Seafordensis. Seaford. 



II.- — The Age of the Maitai Series oe New Zealand. 

 By C. T. Trechmann, M.Sc, F.G.S. 

 (PLATES IV AND V.) 

 Previous Views on the Age of the Maitai Series. 

 f]pHE question of the age of the Maitai Series is one of the most 

 1 important which concern New Zealand geology, and one which 

 has aroused the greatest controversy and uncertainty. F. von 

 Hochstetter, 1 before any distinctive fossils had been found in these 

 rocks, considered that the "Maitai Series", which form the hills 

 bounding on the east and south-east the strip of fossiliferous Trias of 

 the Nelson area, were of Triassic age, and underlay the sandstones 

 with Monotis salinaria? In 1873 P. W. Hutton s referred the Maitai 

 to the Jurassic on the supposed occurrence of Inoceramus. A. McKay 4 

 in 1878, during the survey of the Nelson district, found several 

 fossils, obviously of late Palaeozoic age, in the Maitai Limestone of 

 the upper part of the lower Wairoa Gorge opposite a place called 

 Martin's Saw-mill. Sir J. Hector 5 identified these as Spirt/era 

 hisulcata, Productus brachythc&rus, Cyathopkyllum, and Cyathocrinus. 

 McKay also surveyed and collected from the Maitai slates and 

 argillites at Wooded Peak, on the Dun Mountain Tramway, some 

 five miles east of Nelson. A large bivalve shell having the prismatic 

 structure and general outline and concentric plication of Inoceramus 

 occurs here. McKay, however, in his report adds that " there are 

 material differences between this shell and the ordinary forms of 

 Inoceramus which may warrant its being considered the type of 

 a new genus". These words are of great importance, since lie 

 clearly states his conviction that fragments of a prismatic shell which 

 occur with the Carboniferous fossils in the Maitai Limestones belong 

 to the same shell as that which occurs in the slates on Wooded Peak. 

 There can be no question but that it is the same shell. Since the 

 finding of the above-mentioned fossils the Palaeozoic age of the Maitai 

 Series does not seem to have been seriously questioned till 1903, 

 when Professor J. Park 6 stated his opinion that the Maitai Series 



' F. von Hochstetter, New Zealand, 1867, p. 57. 



2 Now known as Pseudomonotis Bichmondiana. 



3 Reports of Geol. Explorations, 1873-4, p. 34. 



4 Reports of Geol. Explorations, 1877-8, issued 1878, pp. 124, 132. 



5 Reports of Geol. Explorations, 1877-8, Introduction, p. xii. 



6 " On the Jurassic Age of the Maitai Series " : Trans. N.Z. Inst., vol. xxxvi, 

 p. 431. 



