BY D. MAWSON. 451 



As the track proceeds it descends rapidly to the bed of the 

 Wai Bubo, passing downwards from foundation -beds of the soap- 

 stone class over massive agglomerates and interstratified tuffs to 

 unconformable Miocene limestone (208, 210, 211c, 212, 223) 

 tilted at an angle of 55°, so well exposed along the river banks 

 (Plate xix.). Further on, nearer to the ford, better exposures 

 of the mineral tuffs (Sec. 3, §4) dipping 28° due S. are obtained 

 capping the older Miocene series. At the ford, on the north side, 

 the mineral tuffs are replaced by agglomerate beds which are 

 capped directly above by the recent coral limestone. 



Tasiriki itself is within easy distance of many interesting 

 spots. Immediately above the cove on the hillside are soft 

 foundation-beds yielding very numerous fossil forms, amongst 

 which the following have been recognised : — 



Brachiopoda — 1. 



Pelecypoda—\, 5, 6, 8, 15, 16, 18, 20, 21, 27, 2'8, 29. 



Scaphopoda — 1, 2. 



Gastropoda— I, 2, 3, 4, 6, 7, 10, 11, 13, 14, 16, 17, 18, 22, 23, 

 25, 27, 28, 29, 30, 31, 32, 33, 36, 37, 40, 42, 43. 



Pteropoda — 1, 2, 3, 4, 5, 6. 



Hydrocoralliiue — 1 . 



Corallince — 3. 



Echinoidea — 1 . 



The rocks forming the southern breakwater to the bay are an 

 interesting type of conglomerate, in which water-worn volcanic 

 pebbles several inches in diameter, such as constitute the beaches 

 in the vicinity, are bound together by calcareous organisms. 

 Above, where the pebbles become Jess numerous, corals make 

 their appearance. 



To the north on the hills behind Penanbo, and as far as 

 C. Ukuani, lavas and agglomerates make their appearance 

 underneath the foundation-beds. Specially good outcrops of 

 these are obtained in the vicinity of C. Tsinone; here they contain 

 occasional fragments of limestone, which, however, has lost any 

 trace of organic structure. 



