TRANSACTIONS OF SECTION C. 503 
southern side, have received a direct and reflected wave-path, and therefore have 
two sets of fissures, causing much complication. The author observed a similar 
effect, but much less marked, in 1881. 
The focus seems to have been an enlargement of the former one, and occupies, he 
believes, almost the same topographical position, except that its northern extremity 
is more prolonged. An important fact about the position of this fissure is that it 
nearly corresponds at its southern end with the active fumarolic area of Monte 
Cito, and at its northern with some altered tufas, the result of fumarolic action on 
the beach at Lacco, and therefore is probably along an old fracture, for, at Monte 
Cito, alum was collected in the fourteenth or fifteenth century. 
oe je 
CGROTTAN 
DELLA TERRA 
—_ as ee 
Pace, S.ANGELO 
ys Ree 
SKETCH MAP OF THE ISLAND OF ISCHIA. 
Scale 1 to 120,000. Showing isoseismals of 1881 and 1883, and fissures of each earthquake- 
(width of fissures exaggerated). 
1. Area of maximum and total destruction. 
2 ee a a {2 Area of nearly complete destruction. 
AS ‘ 8. Area of severe injury. 
nu 
H } Ancient craters of eruption. 
Ls es 
5. Dyas versus Permian. By the Rev. A. Irvine, B.A., B.Sc., F.G.S. 
This subject is brought forward for discussion both as having a special local 
interest, and on account of the international importance of the subject in view 
of the Berlin Congress next year, and the progress of the Geological Map of Europe. 
The author, referring to previous papers in the ‘ Geological Magazine’ during the 
year 1882, in which strong reasons were given for abandoning the threefold division 
of the so-called Permian System, and to the discussions raised in the same periodical, 
maintains that the ‘Permian System’ of Murchison, which represents the group 
of strata as marked by three stages, is inapplicable to the English rocks of Post- 
