450 Transactions. 



Its intrusion was evidently subsequent to the deposition of the siliceous 

 hydraulic limestone. The same remarks apply to the Port Albert rock, 

 which forms a small neck about two miles to the east of Port Albert. The 

 dacite of Pukekaroro forms a hill of considerable height which is a pro- 

 minent point over the greater part of the central Kaipara, is surrounded 

 by hydraulic limestone, and is certainly of later origin than that rock. 



The hypersthene andesite of the Funnel was evidently emitted at the 

 time of the deposition of the Pakaurangi beds or immediately afterwards. 

 Small fragments of basic glass were found in the bands of polyzoal and 

 Amphistegina limestone on the Pahi Arm. It is thus evident that volcanic 

 activity was in progress whilst the deposition of the hydraulic limestone 

 was taking place. There are also quarries for railway ballast on the line 

 two miles south of Kaiwaka Station and near Wayby. The rock that is 

 quarried is a volcanic breccia. It is black in colour, and at once gives the 

 impression of formation under submarine conditions. This opinion is con- 

 firmed by microscopical examination, which reveals Foraminifera amongst 

 the volcanic fragments. Amongst the Foraminifera is a specimen of Amphi- 

 stegina. The tufaceous matter includes small greenish grains of augite 

 similar to the augite of the Marahemu basalt. It is thus evident that 

 volcanic activity of an extensive nature took place in this district during 

 and after the deposition of the limestone, for the breccia appears to rest 

 conformably on a phase of the hydraulic limestone. 



Art. XXXVIL— The Wangaloa Beds. 



By Professor P. Marshall, M.A., D.Sc, Professor of Geology, Otago 



University. 



[Read before the Otago Institute. 5th December, 1916 ; received by Editors, 30th December. 

 1916; issued separately, 7th December, 1917 ■] 



Plates XXXIV-XXXVII. 



In a paper dealing with the relations that exist between the Cretaceous 

 and Tertiary rocks, published in the last volume of the Transactions of the 

 New Zealand Institute, a list was given of th.e species of mollusca that had 

 been found in the beds at Wangaloa (p. 114). Further collections have 

 lately been made in the same beds, and these have added a few other 

 species, and have also revealed better specimens of some of the species 

 that had been previously found. Since this formation contains species of 

 mollusca that suggest quite different geological ages, it has been thought 

 advisable to write a fuller paper, giving descriptions of the species that are 

 considered new, as well as illustrations of them. 



I am indebted to many people for assistance in collecting and classifying 

 the fossils — in particular to Mr. H. Suter, whose extensive knowledge of 

 Recent and Tertiary species of New Zealand mollusca was liberally placed 

 at my disposal. Much assistance was also given by the authorities of 

 the National Museum at Melbourne. Mr. C. T. Trechmann also rendered 

 me some aid. I am much indebted to Dr. T. W. Stanton, of the United 

 States Geological Survey, for the comparison of some of the species with 

 typical members of the Calif ornian fossil mollusca. Several people have 

 also given me much assistance in collecting. 



