194 THE ROMAN COMAGMATIC REGION. 
48. VIOLA, C. " Mineralogische und petrographische Mittheilungen aus dem Hernikerlande 
in der Provinz Rom (Italian)." Neu. Jahrb., 1899, I, pp. 93-137. 
49. VOM RATH, G. "Das Albaner-Gebirge. " Zeits. d. deutsch. geol. Ges., XVIII, 1866, pp. 
510-561. 
50. VOM RATH, G. "Die Gegend von Bracciano und Viterbo." Zeits. d. deutsch. geol. Ges., 
XVIII, 1866, pp. 561-585. 
51. VOM RATH, G. "Monte di Cuma, Ischia, Pianura. " Zeits. d. deutsch. geol. Ges., XVIII, 
1866, pp. 607-639. 
52. VOM RATH, G. "Die Umgebungen des Bolsener Sees." Zeits. d. deutsch. geol. Ges., XX, 
1868, pp. 265-307. 
53. VOM RATH, G. "Zwei Gesteine der Rocca Monfina." Zeits. d. deutsch. geol. Ges., XXV, 
1873, pp. 243-247- 
54. WASHINGTON, H. S. "On Some Ischian Trachytes." Am. Jour. Sci., I, 1896, pp. 375-385. 
55. WASHINGTON, H. S. "Italian Petrological Sketches: I, The Bolsena Region." Jour. Geol., 
IV, 1896, pp. 541-566. 
56. WASHINGTON, H. S. "Italian Petrological Sketches: II, The Viterbo Region." Jour. 
Geol., IV, 1896, pp. 826-849. 
57. WASHINGTON, H. S. "Italian Petrological Sketches: III, The Bracciano, Cerveteri, and 
Tolfa Regions." Jour. Geol., V, 1897, pp. 34-49. 
58. WASHINGTON, H. S. "Italian Petrological Sketches: IV, The Rocca Monfina Region." 
Jour. Geol., V, 1897, pp. 241-256. 
59. WASHINGTON, H. S. "Italian Petrological Sketches: V, Summary and Conclusions." Jour. 
Geol., V, 1897, pp. 349-377- 
60. WASHINGTON, H. S. " Some Analyses of Italian Volcanic Rocks." Am. Jour. Sci., VIII, 
1899, pp. 286-294. 
61. WASHINGTON, H. S. "Some Analyses of Italian Volcanic Rocks, II." Am. Jour. Sci., IX, 
1900, pp. 44-54- 
62. WILLIAMS, J. F. "Ueber den Monte Amiata in Toscana und seine Gesteine." Neu. Jahrb., 
B. B. V, 1887, pp. 381-450. 
To these may be added the following general works which contain descriptions 
of some types. 
63. LACROIX, A. Les enclaves des roches volcaniques. Macon, 1893. 
64. ROSENBTJSCH, H. Mikroskopische Physiographic der massigen Gesteine. Stuttgart, 1896. 
65. ROTH, J. Allgememe und chemische Geologic. Berlin, 1883. 
66. ZIRKEL, F. Lehrbuch der Petrographie. Leipzig, 1894. 
