244 



A NATURALIST IN THE PACIFIC 



CHAP. 



Fourth Order of the Olivine-Basalts. 



Characters. — Olivine scanty. Felspar-lathes of the groundmass 



in flow-arrangement. 



Formula. — OHv., matr., pane, flu. 



Sub-order. 



Pyroxyene 



of the 



groundmass. 



10. 



Granular 



(gran. ) 



ii. 

 Prismatic 

 ( prism ) 



12. 



Ophitic 

 (oph.) 



Section. 



Genus. 



Species. 



Presence or 

 absence of plagio- 

 clase phenocrysts. 



19. 



Plagioclase 



phenocrysts 



( phen. ) 



Character 



of the 



phenocrysis. 



20. 



No plagioclase 



phenocrysts 



( non-pken.) 



21. Phen. 



22. Non-phen. 



Glassy plagioclase 



phenocrysts 



( vitr. ) 



38. . 

 Opaque plagioclase 

 phenocrysts 

 (opac. ) 



39- 



Large phenocr}^sts 



of olivine and 



pyroxene, over 



2 ram. {magn.) 



40. 

 Small phenocrysts 

 of olivine and some- 

 times pyroxene, 

 j_ under 2 mm. (parv.) 



Length 



of felspar 



lathes. 



02 — - i mm. 

 •1 — -2 „ 

 •2— "3 „ 

 '3 '5 " 



•02- 

 1- 



•O- 



■1 mm. 

 •2 „ 

 '3 " 

 ■5 » 



•02 — 'I mm. 

 •1 — -2 ,, 

 •2- 



■3— - 5 



53 



J ? 



J" 41. Vitr. 

 \ 42. Opac. 



•02 — "I mm. 



•I— -2 ,, 



•2— "3 „ 

 '3 — '5 ■■> 



"i mm. 



Number of 

 specimens. 



2 



12 



6 



Not repre- 

 sented. 



! 



Not repre- 

 sented. 



Not repre- 

 sented. 



Not repre- 

 sented. 



