164 THE ROMAN COMAGMATIC REGION- 
The salfemane class is much less abundantly represented, the only subrang 
being albanose (III. 8. 2. 2), of the romal, saccal, or boval types [leucitite], and 
is met with at several points about the lake, both north and south. 
It is seen that this district is comparatively simple magmatically, the largely 
predominant subrangs being braccianose and vicose, with relatively small amounts 
of beemerose, vesuvose, and albanose, while the total absence of such widespread 
subrangs as vulsinose and ciminose is very remarkable. Another important char- 
acteristic is the fact that the types are invariably leucitic, which is probably connected 
with the uniformly lenic character of the subrangs, though some of these, as beem- 
erose and vicose, assume non-leucitic modes elsewhere. 
Although the more northern and much of the eastern portions of this district 
are inadequately known, yet the general distribution of magmas described above 
would lead us to suspect that here, as at the Vulsinian District, there is a progressive 
magmatic change from north to south, the femic constituents increasing and the 
silica diminishing in this direction. 
LATIAN DISTRICT. 
This small district, with a comparatively simple volcanic structure, is even 
more uniform in its eruptive products than the one just described. The persalanes 
are represented only by the very rare tavolatal appianose [haiiynitic leucite- 
tephrite], which is found only as blocks in tuff. Of the dosalanes only one subrang 
can be surely identified, that of braccianose (II. 7. 2. 2), to the hernical type of 
which [leucitite] many flows can be referred. The salfemanes are probably the 
most abundant, but all belong to one subrang, albanose (III. 8. 2. 2), mostly of 
the romal and saccal types [leucitite], but in some cases of the melilitic boval type 
[cecilite]. 
The district is thus very monotonous, and is notable for the highly femic 
character of its products and their large content in leucite, as well as for the total 
absence of non-leucitic rocks. 
HERNICAN DISTRICT. 
This very small district resembles the Latian in the general character and 
uniformity of its rocks. None belonging to persalane occur, nor are ciminose or 
vicose represented among the dosalanes. Of the rocks of this class the majority 
fall in braccianose (II. 7. 2. 2) [leucite-tephrite]. with a few probably in vesuvose 
(II. 8. 2. 2) [leucitite] and one probably, though doubtfully, in fiasconose (II. 7. 
3. 2) [leucite-basanite]. The subrang albanose (III, 8, 2, 2) of salfemane is appar- 
ently as common as braccianose, the rocks being of the saccal type [leucitite]. 
AURUNCAN DISTRICT. 
As our knowledge of the rocks of this district is far from complete, a descrip- 
tion of it must be regarded as provisional and subject to future corrections. The 
persalane rocks seem to be quite common, two subrangs being represented, 
