PLATE I. (Microphotographs) 



Lavas of the Somma. 



Basaltic baudaite almost free from.phenocrjsts of mafic minerals 

 (the 1st type of the somma lava). See pp. 67-72. 



Fig. 1. — ^Somma lava with the grouudmass of a-type (pp. 68 & 70). Here 

 the crystallinity and gi"anularity are low, and anhedral magnetite 

 disseminates finely among the other components. The specimen is from 

 the lava delta of Okata on the north coast (PI. VI. GA 8). x70. 



Fig. 2. — Somma lava with the gToundmass of the same type as thç above, 

 l)ut somewhat higher both in crystallinity and granularity. The specimen 

 was collected from the uppermost lava exposed on the western ring- wall 

 at the point 800 m. to S.S.W. of Kagamihata. x 70. 



Fig. 3. — Somma lava with the gromidmass of /?-type (pp. 68 & 70). 

 Specimen from the uppermost lava exposed at Tatsunokuchi (PI. VI. 

 BC 3). x70. 



Fig. 4. — Somma lava with the same groundmass fextm'e as the above but 

 with extremely fine gi'anularity (0.008 mvi. in average diameter of the 

 component minerals). Specimen fi'om the lava exposed at the point, 

 about Ihn. to N.N.W. of Habu, marked (g) on PI. V. 3e. X 70. 



Fig. 5. — Somma lava with higher crystallinity. The size of magnetite is here 

 as large as 0.08 mm. across. Specimen from the uppermost lava on the 

 sea chff to the east of Saslukiji (PI. VI. DE 4). x 70. See. p. 70. 



Fig. 6. — Somma lava with similar texture to the above, but with still larger 

 magnetite crystals. The specimen was taken from the sea cliif to tlie 

 west of Sendzu (PI. VI. GA 7). x 70. 



