Park. — On the Jurasdc Age of the Maitai Series. 441 



The Athyris bed at the close of the Trias at Shaw Bay 

 contains both Bastelligera and Clavigera, the latter in great 

 abundance and in a fine state of preservation. The two 

 species of Clavigera (Athyris) which occur in Well's Greek 

 horizon are both represented at Shaw Bay. 



The sub-genera Bastelligera and Clavigera are so dis- 

 tinctive in structure and widely distributed that they are of 

 'the highest value for the identification of Trias rocks wher- 

 ever they occur in New Zealand. In my examination of 

 the Trias in Nelson, Nugget Point, and Hokonui Hills I 

 found them only in the highest fossiliferous horizon. 



The Director of the Geological Survey, in his " Outlines of 

 New Zealand Geology," 1886, states that Bastelligera occurs 

 in the Otapiri and Wairoa series — that is, in both the Upper 

 and Middle Trias. If this is the case Bastelligera has no 

 zonal value. But I can find no reference in the Geological 

 Reports to its occurrence below the Otapiri series except 

 at Weil's Creek, where the theory of inversion of the Triassic 

 system suggested by Mr. McKay makes the Clavigera beds of 

 the Otapiri series appear to be at the base of the Trias. 



The genus Clavigera, so far as I have been able to dis- 

 cover, occurs only in the highest marine horizon of the Trias, 

 and, having a definite age-limit, it assumes a zonal value. 

 Hence its occurrence in a group of beds in Shaw Bay, in 

 Otago, and in Well's Creek, in Nelson, tends to indicate the 

 correlative age of these distant beds. But the Shaw Bay 

 Clavigera beds overlie the Mytilus beds, therefore the Clavi- 

 gera beds in Well's Creek should also overlie the Mytilus beds, 

 and I have already shown that they do so. 



Thus in both districts the stratigraphical and palseonto- 

 logical evidence clearly proves the superior position of Mr. 

 McKay's so-called Permian beds in Well's Creek, and sup- 

 ports the correlation of the conformably overlying Maitai 

 formation in Nelson with the conformably overlying Mataura 

 formation in southern Otago. 



An examination of the geological structui-e of the region 

 between Nugget Point, Waikawa, and Mataura has confirmed 

 me in the belief that the Mataura and Maitai formations of 

 Sir James Hector represent the same series of beds. Both 

 formations follow the Upper Trias conformably, and both 

 consist of a great succession of slaty shales and sandstones 

 singularly free from organic remains. The Maitai rocks con- 

 tain Inoceramus , annelid-markings, and indistinct plant-re- 

 mains ; the Mataura series Inoceramus, annelid-markings, and 

 plant-remains. 



As the Carboniferous age of the Maitai formation can 

 no longer be maintained, and since the term "Maitai" has 

 grown almost synonymous with " Carboniferous," to avoid 



