384 Transactions. — Geology. 



denudation, the lower fossiliferous Athyris bed (No. 3) stands 

 up like the wall of a house, presenting an even surface 70 ft. 

 high and 100 ft. long thickly incrusted with shells of Athyris 

 which have weathered out of the matrix. 



By far the greater proportion of the forms are impunc- 

 tate Athyris, but the large Spirifcnna (EastelUgera), possess- 

 ing fine comb-like dentition along the hinge-line, is not un- 

 common. 



In the middle and upper fossiliferous zones Athyris are 

 sparingly scattered in a sandstone matrix. 



The Athyris beds form the natural close of the Trias for- 

 mation. On stratigraphical and palseontological grounds they 

 may be safely correlated with the Athyris beds forming the 

 close of the Trias at the Wairoa Goi'ge and Eighty-eight 

 Valley iu Nelson, where the sequence of fossiliferous horizons 

 shows a remarkable correspondence with that of Shaw Bay. 



It is impossible in such widely separated districts to 

 correlate bed with bed, but a comparison of the sequence 

 clearly demonstrates a general harmony in the order of 

 succession of the different zones. 



In Eighty-eight Valley the sequence of the Trias, as indi- 

 cated by the fossiliferous zones, is as follows : — 



1. Athyris beds. 



2. My tikis beds. 



3. Trigonia and Spirtgera beds, with Mytihis. 



4. Halohia and Spiriferina beds. 



5. Plant beds. 



The Athyris is a very unusual form, and is of great zonal 

 value. It has been identified at the close of the Trias 

 throughout New Zealand. Its distinctive characters are 

 referred to in my paper on the Jurassic age of the Maitai 

 formation, which appears in another part of this volume. 



Monotis salinaria var. richmondiana, Zitt., which is so 

 abundant in some parts of the Trias of Nelson and Southland, 

 generally occurs in a horizon above the Trigonia beds. 



In his report of 1873 Mr. McKay mentions tliat the upper 

 conglomerate divides an Ammonite bed into two parts. The 

 Ammonite bed is described as being " very rich in chambered 

 shells of various genera"; but, unfortunately, we were unable 

 to find any of the genera reported by McKay, and succeeded in 

 discovering only one fragment of an anmionoid shell among 

 the beach debris. Dr. Marsliall, who visited this place witli a 

 party of his students in July, was more successful. He dis- 

 covered a number of Ammonites, but they were all broken and 

 fragmentary. 



The great assemblage of sandstones, claystones, and slaty 



