Vol. t;4.] MK. H. WOODS ON ROCKS FROM EOTFMA. 11 



consists of minute, but long, plagioclase-felspars (with a few larger 

 crystals of the same mineral), augite, and magnetite. The small 

 felspars have a parallel arrangement. The specimen from Mafiri is 

 a fine-grained rock, in which the felspars have no regular arrange- 

 ment. 



3. Oli vine-Basalts from Savelei Point_, base of Hoi^ 

 and base of Vavasse (opposite Sol Kopi) . 



The specimen from Hoi is a greyish compact rock with light 

 green crystals of olivine. Microscopic examination shows that it is 

 fine-grained and not decomposed ; it consists mainly of a mass of 

 small, lath-shaped, plagioclase-felspars and augite, with larger crystals 

 of augite and olivine. Magnetite is abundant. The felspars have 

 a fairly well-marked parallel arrangement. 



The rock from Savelei Point is darker and somewhat vesicular, 

 resembling in general appearance the specimen from Tarasua Point, 

 but containing olivine. 



4. Ashes from Sol Kopi_, Afaga^ Howa^ Kugoi, Kiliga 

 Pointy and Sororoa. 



These are light-coloured rocks, varying in texture and compact- 

 ness. The specimen from Sol Kopi is composed mainly of rather 

 large fragments of glass containing numerous vesicles, and a fair 

 number of crystals of augite. The specimen from Afaga is similar, 

 but lighter in colour and finer- grained. 



5. Calcareous Sand from Noatau, Oinafa, and Matusa. 



This is a white, loosely-compacted rock, composed of calcareous 

 grains, often as much as 3 mm. in diameter. Microscopic exami- 

 nation shows that the grains consist of calcareous algse, fragments 

 of echinoderms, and corals ; a few pieces of volcanic rock (? andesite) 

 are also seen. In a more compact example the cementing-material 

 is calcite. 



Discussion-. 

 Prof. J. W. Jtjdi) and Mr. Mark spoke, and the Author replied. 



