Geol. Mag. 190!). 



Platk XXIV. 



'^::^/, 



^ 





.'to/ 





Thiise III, Monte Somnia, showing- viist 

 difference hetAveeii tlie jiumire ejected 

 ;it the coiimieiicemeiit and middle of 

 an explosive eruption. 



7* ♦7^ /v "'V.^i > 



Vr. II. J. Jo/insloii-Liivis microiihot 



Pumices ami Pumiceous Scoria from explosive eruptions, Monte .Somma 

 and Vesuvius. 



