184 A MEMOIK OF EGBERT ETHERIDGE, F.R.S. 
from the base of the Black Shales well into the Red 
Keuper Marls ! ^ It seems hopeless now to attempt to 
disentangle the meaning of these “ Tea-green Marls ” ; 
they can only be regarded as a local phase of the passage- 
beds that occur between the main mass of red and varie- 
gated Keuper Marls and the Rhaetic Beds. As remarked 
by the present writer, “ In some localities the more marked 
boundary would be taken at the base of the Black Shales, 
as the Grey Marls appear more closely linked with the 
Red Marls ; but in other localities the Grey Maris present 
features markedly different from the Keuper Maris, and 
appear more closely connected with the Black Shales 
and White Lias.” ^ Much may be said locally in favour 
of either view ; thus, Edward Wilson strongly supported 
the view that the Grey Marls should be classed as Keuper, 
while the results of the latest observations in South 
Wales show the intimate local connection between the 
Keuper Marls and Rhsetic Beds. 
Etheridge’s most important paper was that “ On the 
Physical Structure of North Devon, and on the Palseonto- 
logical Value of the Devonian Fossils.” It was prepared 
by request of Murchison as an answer to the heterodox 
views expressed by J. Beete Jukes, then Director of the 
Irish branch of the Geological Survey. On and off since 
1852 ^ Jukes had experienced doubts with regard to the 
Devonian as a separate system, believing that the slates 
were in the main Lower Carboniferous and the sandstones 
Old Red Sandstone. Matters were brought to a climax 
when his paper “ On the Carboniferous Slate (or Devonian 
Rocks) and the Old Red Sandstone of South Ireland and 
North Devon,” was read before the Geological Society 
1 See paper “ On the Rhaetic Beds of Penarth and Lavernock,” 
Trans. Cardiff Nat. Soc., voL hi. p. 39. See also Etheridge’s Strati- 
graphical Geology, p. 342. 
2 Geology of England and Wales, ed. 2, 1887, p. 245. 
3 Letters, etc. of J. B. Jukes, 1871, p. 561. 
