182 ART. 3. — B. KOTÙ : 



mncli modified in appearance from the original smooth surface. 

 The specimens were hammered off three and a half months after the 

 extravasation, when the lava-field above sea surface was still fuming 

 with the s a 1 m i a c and other vapors, while the submarine portion 

 was already partially covered with sea mosses and serpula worms. 



The submarine lavas that were discharged from vents (secche) 

 in the bottom, and those (bocche) from land consolidated in the 

 subaqueous environment, difier greatly in their mineralogical 

 development of magma ; the former resemble an artificial sl^ig, 

 well exemphfied in the rock of the new islets of the An-ei era 

 (pp. 54, 176), while the latter are more like the normal rock, 

 though both consolidated at the sea-bottom. The former are foamy 

 brown glass, containing fibrillated augite microlites (clino-enstatite 

 or enstatite- augite) mingling with only few or none of feldspar laths 

 and magnetite gi-ains (PI. XIX. Figs. 6-7 ; PI. XX. Figs. 2-4), but 

 the latter, now under consideration, are more crystalline, as in the 

 case of the new land rocks described above. 



The rock is dull-grayish black and cavernous, dopatic to 

 sempatic, dotted with the feldspar phenocrysts (2 mm., rarely 

 4 vun.) ; coccolithic or lumpy, due to chilling under water, result- 

 ing in the formation of regular, sometimes diverse networks 

 (4 mm. in diameter) of clefts, lined with limonitic iron ores and 

 dusts. The same structure also appears in subaërial flows, when 

 it is drastically cooled at the lateral margin, e.g., at Sambon-gachi 

 on the western flow (p. 72, footnote 4, and Text-fig. 18b). 



The phenocrystic plagioclase (labradorite) is full of brown 

 glass due to temporary retrogressive corrosion, and is zonal- 

 structured owing to rapid growth of the interior and also renewed 

 growth in a later phase in another environment. Microphenocrysts 

 of olivine are almost always present (PL XIX. Fig. 7 ; PL XX. Fig. 3) 



