On the Vents of Hot Vapor in Tuscany. 207 
- The eastern or inland ridge rises boldly up into the mountains 
which proceed from the north of Monte Vaso to Castellina Marit- 
_ tima on the south, and it is-in reference to this group of hills, on 
the eastern part of which Monte Catini is situated, that I specially 
call attention, as it affords ample materials for settling the ques- 
tion which has arisen between Professor P. Savi and Mr. W. J. 
Hamilton on the one hand, and the late Professor Leopoldo Pilla 
and myself on the other. The two former have endeavored to 
show that whether in its globular and amorphous form, or in Its 
thin-bedded state,* the rocks they call ‘‘ gabbro rosso” are meta- 
morphic ; whilst Professor Pilla and myself contend that the 
amorphous, variolitic gabbro must have been erupted in a molten 
state, whether we consider its composition and unbedded condi- 
tion, or the part it has played in protruding through, overturning, 
breaking, and altering the pre-existing strata. And although 
my deceased friend Pilla has to a certain extent published this 
opinion, he has not sufliciently illustrated his views, an am 
therefore the more anxious to do him justice, and to adduce some 
of the reasons he assigned when we visited the tract together. 
spected natural sections, where the gabbro had not only penetrated 
the alberese limestone, but had thrown it off in shreds, contorted 
fragments, and folds on the sides of the eruption. ow, the red 
gabbro which had manifestly thus acted was entirely an unbedded, 
amorphous, felspathic mass, for the most part made up of spheroidal 
concretions having a variolitic structure, 7. e, with small pustular 
or globular surfaces in each of the folds or concentric layers into 
Sabre ion of Savi's descripti . Journ, Geol. Soc. 
Voli, p, oo nitins translation of Savi’s description, Quart. Journ. Geo : 
