F280 
XXXV. 
ON HOZOONAL STRUCTURE OF THE EJECTED BLOCKS 
OF MONTE SOMMA. By PROFESSOR H. J. JOHNSTON- 
LAVIS AND DR. J. W. GREGORY, F.G.S. 
[Abstract of a Paper published in extenso in the ScteNTIFIC TRANSACTIONS OF THE 
Royat Dusuin Society, Vol. V.] 
Tue authors show that the limestone blocks, of Mesozoic age, in 
Monte Somma have frequently become metamorphosed into 
crystalline masses consisting of alternating bands of calcite and 
various silicates. The authors regard the silica, magnesia, &c., 
as derived from the igneous rock by chemical interpenetration 
and interaction. Where the silicate, as often happens, is olivine 
(montecellite), or a pyroxene, a complete simulation of the struc- 
ture of Hozoon Canadense is produced. The layers of silicates 
occur parallel to the surfaces of any igneous vein that may have 
intruded into the limestone, and they become closer to one another 
in the areas farther removed from contact. ‘he “proper wall,” 
the “stolons,” and in places the “canal system” of Hozoon are 
recognizable under the microscope; and the authors adduce 
evidence to show that the typical eozoonal limestone of Canada 
may have arisen similarly as a product of contact metamorphism. 
