1868] Siluria. 197 
oldest of the British stratified deposits; the reality of this, the 
latest of Sir Roderick’s discoveries, being then still sub judice. In 
this edition we find a record of the correlation of this Fundamental 
Gneiss with the Hozoon containmg Laurentian rocks of Canada, dis- 
covered by Sir William Logan, and about which, as the sepulchre 
of the most ancient of all known fossils, we have lately heard so 
much. 
It speaks well for the breadth and catholicity of Sir Roderick’s 
mind that he should have been able at once to acknowledge the 
reality of this discovery, and to grasp its important bearing on the 
geology of our own islands. He was also the first to recognize 
the high probability of his “ Fundamental Gneiss” being of the 
same age as the Laurentian rocks, and to abandon the name he 
had himself given to the Scotch series, adopting that applied by Sir 
William Logan to the far more extensive development of them in 
Canada. Were anything still wanting to show the nature of our 
author’s exalted opinion of Sir William Logan’s discovery, it would 
be found in the graceful dedication of this edition to the eminent 
Canadian geologist. 
Another most important alteration has been made by the author 
with reference to the reptiliferous sandstones of Elgin and Ross- 
shire. The strata conformably overlie and apparently pass into 
deposits undoubtedly belonging to the Old Red Sandstone ; but they 
long ago yielded remains of reptiles allied to those found in Triassic 
rocks of other localities. Sir Roderick Murchison, reasoning upon 
the stratigraphical evidence, had hitherto classified these upper 
sandstones with the Old Red deposits, while paleontologists con- 
sidered that if reptiles of Triassic affinities existed in the Devonian 
or Old Red period “ ’twas passing strange.” Fortunately, however, 
a specimen from the undoubted Triassic deposits of Warwickshire 
has lately been identified by Professor Huxley with the Hyperoda- 
pedon,—a reptile which had previously been obtained from the 
sandstones of Elgin,—and thus this vexed question has been decided 
in favour of Paleontology, and Sir Roderick Murchison has yielded 
to the stubborn fact, and excluded the portion of his former editions 
which treated of these strata as belonging to the Old Red Sand- 
stone. 
Our knowledge of the geology of other portions of Great 
Britain is also more complete than at the date of the publication 
of the last edition; and Sir Roderick has taken especial care to 
bring his work up to the present state of the science, so far, at 
least, as he can admit the views of other investigators. He has 
personally been concerned with Professor Harkness in the deter- 
mination of the Permian age of large tracts in Westmoreland, 
which had previously been mapped as Triassic; and Mr. Geikie has 
shown that the red sandstones overlying the Ayrshire coal-measures 
