PETROGRAPHY. 49 
Occurrence. This type is found only in the Sabatinian District, so far as is 
known with certainty. The most prominent locality is a massive flow on the north- 
west shore of Lake Bracciano, below Poggio Muratella, the lava being derived, 
according to Moderni, from the cone of Poggio Tondo to the northwest. The type 
also forms blocks in bedded tuffs in the railroad cut about 2 km. southeast of Oriolo 
station, which are probably from the same cone. Another excellent locality is on 
the north shore of Lake Bracciano, just west of Vicarello, at the end of a large lava 
stream from the cone of Monte Levo. 
A rock which may be provisionally referred to this type occurs near Acqua- 
pendente (especially at a quarry at the east gate), north of Lake Bolsena, in the 
Vulsinian District. No analysis has yet been made of this, and although it is 
certain that it falls in the same class, order, and rang as beemerose, it is possibly in 
the dopotassic subrang, which is as yet unrepresented. From the descriptions of 
Bucca and Klein it is possible that rocks belonging to the same subrang, or that of 
beemerose and of the same or similar type, occur elsewhere in the district, especially 
in the northwest, around the Latera Volcano. 
Name. The name of the subrang is derived from the locality, Beemerville, 
near which a well-known type occurs. That of the type is derived from that of 
the district where it occurs. 
In the prevailing systems of classification these rocks would be called either 
leucite-trachyte or leucite-phonolite, according to Zirkel, or leucite-phonolite or leu- 
citophyre, according to Rosenbusch, as one does not or does lay stress on the pres- 
ence of nephelite. In a previous paper I used the name leucite-phonolite in the sense 
of Zirkel, as the presence of nephelite and hauyne, even in rather small amount, 
seemed to be of sufficient importance to distinguish these rocks from other similar 
ones of the region which are free from these lenic minerals. 
SABAT1NAL BEEMEROSE. I. 6. 1. 3. 
Megascopic characters. Very light gray, compact, porphyritic. Leucite phenocrysts 
common, not well shaped, from 2 to 10 mm., often yellowish and waxy luster, very few inclu- 
sions. Some augite phenocrysts, about i mm. long, black. Groundmass: light gray, aphanitic. 
Specific gravity 2.551 at 10 C. 
Microscopic characters. Holocrystalline, megaporphyritic, dopatic. Phenocrysts: about 
12 per cent, leucite, aegirite-augite. Groundmass: about 88 per cent, confused, hypautomorphic 
granular fabric, soda-orthoclase, leucite, hauyne, nephelite, aegirite-augite, magnetite, apatite, 
titanite. 
Soda-orthoclase, Or 3 Ab 2 . Phenocrysts: none. Groundmass: about 70 per cent, 0.2 to 
0.4 mm., subhedral, stout prisms, arrangement diverse. 
Leucite. Phenocrysts: about 10 per cent, 2 to 10 mm., subhedral to anhedral, equant to 
irregular, twinning common, inclusions of augite and groundmass rare. Groundmass: about 5 
per cent, 0.05 to o. 10 mm., anhedral, equant, few inclusions, sometimes altered to pseudoleucite. 
jEgirite-augite. Phenocrysts: about 2 per cent, 0.5 to i.omm., subhedral, stout pris- 
matic, olive-green, pleochroic. Groundmass: about 5 per cent, 0.02 to 0.05 mm., anhedral, 
prismatic, light olive-green. 
Nephelite. Groundmass: about 5 per cent, anhedral, cement about the other minerals 
of the groundmass. 
