448 Transactions. 



*Corbula maeilenta Hutton. 



Gorbula n. sp. 

 *Panopea zelandica Q. & G. 



Gardita (Glans) n. sp. 

 Ghama huttoni Hector. 

 Gorbula canaliculata Hutton. 

 Gorbula kaiparaensis Suter. 



Of these 113 species only twenty- three are Recent, a percentage of 19-9. 

 The genera Dolicholatirus, Goptochetus, Grenilabium, and Spondylus have 

 not previously been foi;nd in the New Zealand fauna, fossil or Recent. 

 The species Acteon craticulatus, Cadulus delicatulus, and Thyasira flexuosa 

 have not previously been found fossil. 



The rather low percentage of Recent species may be due to the northern 

 locality, for it-is probable that many species would tend to recede north- 

 wards as the climate became somewhat colder in the Pleistocene. The 

 absence of littoral waters any considerable distance farther north would 

 have caused some of these species to become extinct. This also may 

 account for the presence of four genera which are now absent from the 

 New Zealand fauna. The age of the Pakaurangi Point beds is probably 

 about that of Target Gully if the suggestion made is regarded as valid so 

 far as the extinct species are concerned. 



Rocks op Igneous Origin. 



Igneous rocks have been found in the following localities : The Otamatea 

 Funnel, Mohinui (or Marahemu), Port Albert, Pukekaroro. 



Conglomerates of the Otamatea Funnel. 



A considerable outcrop of volcanic rocks is found on the south-eastern 

 side of the Funnel. It appears to be in situ in this locality, though it was 

 seen in the form of large boulders only. 



This rock is moderately coarse, and shows feldspar crystals of consider- 

 able size in the hand-specimens. In section these crystals are found to be 

 irregular, often zoned, and always twinned, showing in sections at right 

 angles to the brachypinacoid an extinction angle of 30°, thus indicating a 

 type of labradorite. Many of the crystals enclose a great number of minute 

 particles of glassy matter and of augite. Hypersthene is abundant in small 

 well-formed crystals showing the usual pleochroism. In one case a crystal 

 of hypersthene is mantled with a thin coating of augite. Augite is infre- 

 quent as compared with the hypersthene. The groundmass consists mainly 

 of minute microlites of feldspar, but there are also many granules of augite 

 and crystals of magnetite, which mineral is also often found enclosed in the 

 crystals of hypersthene. 



Mohinui, or Marahemu. 



Mohinui is the name given on the Admiralty chart, but Marahemu is 

 used on the Survey maps. The rock of which it is composed is black in 

 colour, and it shows conspicuous crystals of feldspar, augite, and olivine. 



In section the feldspar crystals are seen to be irregular, and they are 

 occasionally in aggregates and show zonal structure. The species is 

 labradorite, for the extinction angle in sections at right angles to the 

 brachypinacoid is 32°. The augite is often in well-formed crystals, and 

 is frequently twinned. It may reach 2-5 cm. in diameter, and is of a 

 greenish colour. Olivine is common, and the crystals are sometimes well 

 formed. Most of them show serpentinization along crevices and along the 

 borders. The groundmass is mainly feldspar in microlites. There is also 

 much augite and magnetite. 



