Scientific Intelligence—Geology. 361 
rents of tefrine or grey basalt, and raised the crater of La Tartaruga 
and others in the valley of La Molara, and in the central crater ; at the 
same time ejecting great volumes of purverulent lapilli. It may have 
been coeval with these perfectly regular and comparatively modern 
eruptions, or it may have preceded them, that, after a period so long 
that the surface of the ancient eruptions of peperino were covered 
with vegetation and timber, the tremendous outbursts which forced 
open the craters of Albano and Nemi took place, the former pro- 
ducing some slight ejections of peperino or boiling mud, near Castel 
Gaudolfo ; and at the same time a separate orifice, opening at the foot 
of Monte Cavo, may have discharged into the valley of Marino the 
remarkable variety of peperino described in this paper, and containing 
vegetable stems. A long, perhaps even a final, repose succeeded this 
paroxysm, Even from the very dawn of Italian history these scenes 
of previous turmoil and desolation appear to have enjoyed profound 
tranquillity, and to have been immemorially covered with impenetra- 
ble groves sacred to the sports of Diana. 
“ Tt will be seen, then, that we admit tufas or peperinos of three 
very different periods, one of which is coeval with, or even anterior to, 
the formation of the exterior cone ; another largely developed, which 
accompanied the great breach in it towards the sea; and a third, 
which probably produced some local streams, such as that of Marino, 
which has evidently flowed since the ground took its present con- 
figuration, and was covered with plants. Of lavas, likewise, we must 
admit at least three periods ; 1st, the compact basalts of the outer 
circuit, which, if Von Buch’s theory be correct, have flowed under a 
less inclination than they at present have; 2dly, The well-marked 
lencitic, or partridge-eyed lavas, which form the interior circuit ; 
and, 3dly, the compact basaltic lava which flows past Rocca di Papa 
towards Grotta Ferrata, which is possibly coeval with the dikes oc- 
curring at Capo di Bove and elsewhere. This leaves the origin of 
the lava sperone still uncertain. It is undoubtedly one of the more 
recent products, for it not only overlies the whole of the old basaltic 
series at Tusculum and Nemi, but the leucitic lavas of the newer cone 
at Rocca di Papa. The easiest solution would be to consider it as a 
scoriform basalt ; but even to this there are difficulties, not only mine- 
ralogical, but from position. For how can we connect the mantle- 
shaped covering of Monte Cavo up to its highest point, with the basalt, 
which nowhere attains a height (so far as I know) within several 
hundred feet of it? It is still more difficult to conceive any contin- 
uity between the sperone of the central cone and that of Tusculum, 
which is separated from it by the great valley of La Molara.”—(Pro- 
ceedings of Roy. Soc. Edin., vol. ii., No. 35.) 
4. On Infusorial Deposits on the River Chutes in Oregon. By 
M. Ehrenberg (Monatsb. Acad., Berlin, Feb. 1849, p. 76).— 
