PETROLOGY. 163 
flows about the Cimino Volcano. Leucitic types of ciminose are less common. 
The most so is the viterbal type [leucite-trachyte], to which some of the flows of 
the Vico Volcano doubtless belong, though most of them are in vulsinose. The 
less highly porphyritic bagnoreal ciminose [leucite-trachyte] and martinal cimi- 
nose [leucite-tephrite] are rarer, the former being represented only in the Monte 
Venere, the last eruption of Vico, and the latter by some flows on the northwest. 
The subrang monzonose (II. 5. 2. 3) is a rather rare one, and forms only a few 
flows in the southern portion of Vico. On the other hand, the subrang of vicose 
(II, 6. 2. 2) is abundant, always of the viterbal type [leucite-tephrite], and forms 
numerous flows of the Vico Volcano. 
From the above it is clear that the older Cimino Volcano to the northeast is 
composed almost wholly of harzose, vulsinose, and ciminose, the types of these 
being non-leucitic without exception, so far as known. The Vico Volcano has, 
as the predominant magmas, vulsinose, ciminose, and vicose, with some phlegrose, 
and small quantities of monzonose, leucitic types being somewhat predominant. 
As a whole, then, the district is comparatively simple magmatically, and, as we shall 
see later, the most abundant magmas are those vulsinose, ciminose and vicose 
which are nearest the average composition of the whole region. It is especially 
noteworthy that none of the subrangs, as braccianose and vesuvose, belonging to the 
more lenic orders are found, and that the salfemanes are wholly unrepresented. 
We find here also evidences of progressive magmatic change in the rocks of 
Cimino and Vico, the former being as a whole considerably more salic and higher 
in silica than those of Vico. At each individually there does not seem to be any 
definite spatial distribution, a condition to be expected when it is considered that 
in each case there was apparently but one outlet for the flows. 
SABATINIAN DISTRICT. 
This district resembles the Vulsinian in the complexity of its volcanic struc- 
ture, as well as in the range of its subrangs, though magmatically there are some 
striking differences. 
The persalane class is comparatively rare, neither phlegrose nor vulsinose, 
which are so common in the northern districts, being met with here. Of this class 
the only subrang is beemerose (I. 6. i. 3), the sabatinal type of which [leucite 
phonolite] occurs in the northern portion. Of dosalane the subrang ciminose 
(II. 5. 2. 2) is wholly unknown, but vicose (II. 6. 2. 2) is rather common in several 
types [leucite-tephrite], both to the west and the east of Lake Bracciano. Of the 
subrangs of dosalane, braccianose (II. 7. 2. 2), almost always of the galeral type 
[leucitite], is by far the most common and, indeed, the most characteristic of the 
district. To this division belong nearly all of the extensive flows south of Lake 
Bracciano, as well as some to the east and west. The subrang vesuvose (II. 8. 
2. 2) is also rather common, likewise of the galeral type [leucitite], and is met with 
in the northerly parts of the district. 
