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., pauc.^flu. 



Sub-order. 



Pyroxyene 



of the 



groundmass. 



Section. 



lO. 



Granular 

 (gran. ) 



II. 

 Prismatic 

 ( prism. ) 



12. 



Ophitic 

 {oph.) 



Presence or 

 absence of plagio- 

 clase phenocrysts. 



Genus. 



Character 



of the 



phenocrysts. 



19. 



Plagioclase 



phenocrysts 



{phen.) 



20. 



No plagioclase 



phenocrysts 



( tioji-phen. ) 



'21. Fhen. 



22. Non-phen. 



37- . 



Glassy plagioclase 



phenocrysts 

 ( vitr. ) 



38. . 

 Opaque plagioclase 

 phenocrysts 

 {opac. ) 



39- 



Large phenocrysts 



of olivine and 



pyroxene, over 



2 mm. {inagn.) 



40. 

 Small phenocrysts 

 of olivine and some- 

 times pyroxene, 

 ^ under 2 mm. {pai'V.) 



41. Vitr. . 



42. Opac. 



43. Magn. 



44. Parv. 



Species. 



Length 



of felspar 



lathes. 



Number of 

 specimens. 



•02 — "I mm. 



12 

 6 



Not repre- 

 sented. 



Not repre- 

 sented. 



Not repre- 

 sented. 



Not repre- 

 sented. 



