834 HENRY S. WASHINGTON 



Very similar, if not identical rocks from the western part 

 of the region are described by vom Rath and Mercalli, and Verri 

 also speaks of them. The "biotite-hypersthene-trachyte" from 

 I Capuccini at Monte La Pallanzana described by Rosenbusch^ 

 also belongs here. He speaks of labradorite as abundant. A 

 section of this rock which I obtained from Sturtz belongs appar- 

 ently to the "peperino" described later. Bucca does not men- 

 tion these rocks but describes a "trachyte" from Casaccia, at the 

 southern end of Lake Vico. In this, however, he mentions olivine 

 as visible megascopically, and a plagioclase as abundant both as 

 phenocrysts and in the groundmass so that it is probably to be 

 referred to the following group of rocks. This is also probably 

 the same rock as that from near Ronciglione which Mercalli 

 briefly describes as an "andesitic olivine-trachyte." 



Cifttinite. — The main mass of the Monti Cimini is made up 

 of a peculiar rock, which occurs in streams and perhaps also as 

 domal masses. In several places this rests on Pliocene clays, 

 which have been more or less metamorphosed at the contact.^ 



The proper position of this rock in our classification has been 

 uncertain almost from the first. Vom Rath calls it a trachyte, 

 while Deecke refers it to the augite-andesites, though each 

 acknowledges that the name chosen does not quite agree with 

 the characters of the rock. Vom Rath indeed says that were it 

 not for its sanidine content it would fit better into the augite- 

 andesites ; while Deecke remarks that it approaches basalt on 

 the one hand through its content of olivine, and trachyte on the 

 other by its structure and large sanidines. Bucca describes the 

 rock from Madonna della Querela (which, as Deecke says, 

 belongs here) as a trachyte ; though he mentions, without com- 

 menting on the peculiarity, that the phenocrysts are chiefly of 

 abundant olivine and augite, with few of feldspar. He describes 

 the rock from Fontana di Fiesole as a leucitic trachyte, but 

 speaks vaguely of " distinguishing two parts in the rock, one 

 composed essentially of leucite, the other forming a rock similar 



'RosENBUSCH, Mikr. Phys., II, 771, 1896. 

 2 Vom Rath, op. cit., 299. 



