Pakk. — On the Jtirassic Age of the Maitai Series. 439 



to be related to the peculiar form of Athyris called Clavigera, 

 by the Geological Survey. Should it, however, on examina- 

 tion, prove to be a true Spirifer, it would show that this genus 

 persisted in New Zealand up to the close of the Trias. 



A calcareous, pebbly, and gritty sandstone in Eighty-eight 

 Valley closes the Trias sequence, and occupies the same 

 relative position to the upper granite conglomerate that the 

 limestone (Maitai) does to the same conglomerate in the 

 Wairoa sections. From it I collected Spiriferina (two sp.), 

 one of these the Rastelligera of Hector, Athyris (two sp.), 

 Epithyris, Bhynchonella, Pleurotomaria{7) , Patella, branching 

 corals, Pentacriirtts, and fragments of saurian remains, which 

 may probably be referred to Ichthyosaurus. 



Among the Athyris {S2)irigeraoi D'Orbigny) in this horizon 

 there are two very unusual forms. They have a long straight 

 hinge-line, and a distinct area. They are smooth, gibbose, 

 mipunctate, and possess a gentle mesial sinus in each valve, 

 the sulcation being more distinct in the ventral valve than 

 in the dorsal. The ventral valve is provided with strong pro- 

 minent hinge-teeth, one on each side of the deep triangular 

 notch which in Spirifera is closed by pseudo-deltidium. 



The two species differ widely in external form. One 

 species has rounded cardinal angles resembling those of 

 Athyris expansa, Phillips, or some of the straight -hinged 

 Terebratula, such as Terehratula (Megerlia) siiessi, E. Desl., of 

 the English Lias ; the other, sharp cardinal angles like some 

 species of Argiope. 



The section of the Trias rocks at Eoaring Bay, near Nugget 

 Point, in Otago, supplies the most complete confirmation of 

 the reading of the section in Eighty-eight Valley. Along 

 the coast-line there is exposed a thickness of over 2,500 ft. of 

 strata in one continuous sequence, representing the whole of 

 the Trias formation from the base of the Spiriferina beds to 

 the summit of the Athyris beds. The different horizons repre- 

 sented in this section are as follows, in descending order : — 



1. Athyris beds — coarse pebbly calcareous sandstones. 



2. Coarse sandstones. 



3. Mytilus and oyster bed. 



4. Claystones. 



5. Trigoyiia and Spiriferina beds. 



6. Granite conglomerate. 



7. Sandstones, with beds of claystone. 



8. Breccia conglomerate. 



9. Claystones. 



10. Breccia conglomerate. 



11. Claystones [Halobia lomelli beds). 



12. Porphyrite dyke. 



13. Spiriferina beds — claystones. 



