¥AKT 1.] 
Clark : On Volcanic Foci of Fruptimi in Ike Konkan. 
60 
These localities thus yield an unnsually large numhei’ of Olossopteris, while in 
the Panchet rocks, although its occurrence is undoubtedly established, it is only 
known to occur rarely, and fragmentary. At these localities, however, it occurs 
in the same manner as in the Raniganj group, and we have either to acknowledge 
the closest connection of the Panchet and Raniganj groups (which in this field 
also seems to be shown stratigraphically), or to account for the uninterrupted 
passage of the Raniganj flora into the Panchet grou]!, in which case the close 
relation of both is again shown. It is, of coui’se, possible that the observation.s 
upon which these suggestions are based might bo modified by a revision of the 
survey, but taking the lines as laid down by Mr. G-riosbach, we may now say 
that three-fifths of the species in the Panchet group are those of the Raniganj 
group. 
This mutual relation of the Raniganj and Panchet groups in this field, is so 
far interesting and important, as at the two last-named localities there occurs 
a plant which appears to be a ThinnfeldLa. I shall describe it more closely in my 
Flora of the Lower Gondwftnas. 
Mahadevas. 
In succession to the Raniganj-Panchet rocks the Mahadevas are highly de¬ 
veloped, as in the Satpura basin; and they have proved equally poor in fossils. 
Mr. Griesbach discovered only at one locality some fragments of plants, which 
do not admit of specific determination : one is an Aletliopteris ; the other is doubt¬ 
ful, even as to the genus ; it is either a Tcenlopteris or Glosaopteris. 
The Mahadevas in this area scorn to be to the Panchets in the same close rela¬ 
tion as in the Satpura basin, wdiore the whole Gondwana system is developed, 
from the Talchirs (bottom) to the Jabalpur group (top), and these basins where 
the succession of the several groups is also continuous, are, therefore, of the 
same interest for the correlation of the various group.s. 
On Volcanic Foci of Eecption in the Konkan, hy GeoeCtE T. Clark, Esq.' 
I chanced yesterday, in the library of the Athenamm Club, to meet with the 
two volumes upon the geology of India to which are prefixed your name and that 
of Mr. Blanford, and in vol. I, page 327, I lighted upon some remarks very 
complimentary indeed to myself, but which do not, I think, refer quite correctly 
to what I advanced, now thirty yoai-s ago, on the geology of the western side of 
the Indiatr peninsula, in the neighbourhood of Bombay. I therefore address 
myself to you by lettei’, and I must ask you to excuse the length into which I 
may probably bo betrayed. 
At the time that I reached Bombay in 1844, nothing was known about the 
origin of the trap of We.stei-n India, and I found from Mr. Orlcbar, and, I think, 
' Mr. Clark’s observations ami views upon the trappoan rooks of Western India are much more 
clearly brought out in the letter (dated 25th July 1879) published above, than in his original pa¬ 
pers in the Quarterly Journal Geol. Soc., London, Vol. 111., p. 221, (1847) and Vol. XXV, p. 161 
(1869), from which the notice in the Manual was taken. Tlie oKseurity upon the important ques¬ 
tion of denudation is now quite cleared up.—H. B. Medlicott. 
