THE ROMAN COMAGMATIC REGION. 
Rock Types Occurring in the Roman Region. 
SYMBOL. 
NAME IN QUANTITATIVE SYSTEM. 
NAME IN PREVAILING SYSTEM. 
1.5. i. 4-3. 
I.5-I.3-. 
I. 5. 2. 2... 
I. 5. 2. 2-3 . 
I. 6-5. 2. 3 . 
I. 6. i. 3 . . . 
11-1.1.7.1-3. 
11.4.3.3... 
I-II. 5. 2. 2. . 
II. 5. 2. 2... 
II. 6-5. 2. 2. 
II. S . 2. 3 . . . 
II. 5. 2-3. 2. 
II.5.3.2... 
II. 5-3-3. 
II. 6. 2. 2. . 
II. 7. 2. 2. . 
II. 8-7. 2. 2. 
II. 8. 2. 2... 
III. 8-7. 2. 2. 
III. 7 . 3 . 2. . . 
Ischial nordmarkose-phlegrose.. . 
Cumal phlegrose 
Rotaral phlegrose 
Arsal vulsinose 
Bolsenal vulsinose 
Viterbal vulsinose 
Pallanzanal vulsinose 
Bolsenal vulsinose-pulaskose 
Paglial procenose-pulaskose 
Sabatinal beemerose 
Tavolatal janeirose-appianose. . 
Sorianal harzose 
Arsal vulsinose-ciminose 
Fiescolal ciminose 
Viterbal ciminose 
Bagnoreal ciminose 
Martinal vicose-ciminose 
Arsal monzonose 
Bolsenal monzonose 
Foglianal ciminose-auruncose . . . 
Teanal ciminose-auruncose 
Orvietal auruncose 
Monfinal shoshonose 
Foglianal vicose 
Bagnoreal vicose 
Orvietal vicose 
Vesbal braccianose 
Sommal braccianose 
Galeral braccianose 
Hernical braccianose 
Atrial braccianose 
Scalal vesuvose-braccianose 
Romal vesuvose 
Galeral albanose-jugose 
Fiordinal fiasconose 
Romal albanose 
Saccal albanose 
Boval albanose 
Augite-trachyte (Ischia type). 
Phonolitic trachyte (Cuma type). 
Trachyte obsidian (Rotaro type). 
Vulsinite (Arso type). 
Vulsinite (Bolsena type). 
Leucite-trachyte (Viterbo type). 
Leucite-trachyte (Pallanzana type). 
Vulsinite (Bolsena type). 
Leucite-trachyte (Paglia type). 
Leucite-phonolite (Sabatino type). 
Leucite-tephrite (Tavolato type). 
Biotite-latite (Soriano type). 
Vulsinite (Arso type). 
Ciminite (Fiescoli type). 
Leucite-trachyte (Viterbo type). 
Leucite-trachyte (Bagnoreal type). 
Leucite-tephrite (San Martino type). 
Vulsinite (Arso type). 
Vulsinite (Bolsena type). 
Leucite-tephrite (Viterbo type). 
Leucite-trachyte (Teano type). 
Leucite-tephrite (Orvieto type). 
Biotite-latite (Monfina type). 
Leucite-tephrite (Viterbo type). 
Leucite-tephrite (Bagnorea type). 
Leucite-tephrite (Orvieto type). 
Leucite-tephrite (Vesuvius type). 
Leucite-tephrite (Somma type). 
Leucitite (Galera type). 
Leucitite (Hernici type). 
Leucite-tephrite (Atrio type). 
Leucite-tephrite (Scala type). 
Leucitite (Rome type). 
Leucitite (Galera type). 
Leucite-basanite (Fiordine type). 
Leucitite (Rome type). 
Leucitite (Sacco type). 
Leucitite (Bove type), cecilite. 
In the descriptions of the types the order in which they will be taken up is that 
of their magmatic position, by class, order, rang, and subrang. The divisions 
below subrang that is, grads and subgrads will not be regarded or discussed, as 
it is thought that there are sufficient new terms used in this paper without adding 
to them the many complications and more numerous names which the introduction 
of these minor divisions would involve. It was also thought desirable to determine 
by actual practice whether the refinement in classification implied by the use of 
grads and subgrads in the dosalanes and salfemanes is strictly necessary, or whether 
the general needs of petrographic description and discussion can not be met without 
their use. In a perfect system, carried out to the last details, they are undoubtedly 
logical and necessary, but for practical purposes at present it would seem advisable 
not to discard them, but to avoid the complications that they introduce, and to 
