218 SOME NEW BOOKS [SEPTEMBER 
the Gallery devoted to Scottish Mineralogy and Geology in the Edinburgh 
Museum of Science and Art. 
It is no easy matter to give a summary of the contents of a book which 
contains in a highly-condensed (though perfectly lucid) form, so enormous an 
accumulation of facts. To the readers of Natural Science probably the chief 
interest of the work will centre upon the palaeontological portion, and upon 
such parts of the work as are more or less directly concerned with the Life of 
the Past ; but we may, nevertheless, briefly notice its contents as a whole :— 
The earlier chapters of the history bring before us records of a submarine 
volcanic episode, during the latter part of which the chief organic remains 
which were entombed in the sediments belonged to the Tetragraptidae, Phyllo- 
eraptidae, and a few other Arenig forms of graptolites, together with one or 
two Phylloped Crustacea, and a few Inarticulata, representing the Brachiopoda. 
Next follows a record of much deeper water conditions, during which a large 
area of what is now Southern Scotland would appear to have lain at the 
bottom of an ocean more than 2500 fathoms in depth. It was at this time 
that the now well-known Arenig Radiolarian Chert was formed. (It may not 
be generally known that Mr. Peach was really the first to recognise the true 
nature of this deposit, and that named specimens of it were exhibited in the 
Gallery of Scottish Geology and Mineralogy in Edinburgh a year or more 
before any published description appeared.) Following this ancient oceanic 
ooze comes a record of frequent oscillations of level, and of a gradual elevation of 
at least the western part of the district to above the level of the waves. In 
the meantime the Arenig forms of graptolites had died out, new generations 
of Rhabdophora had gradually come into being, and the conditions favourable 
for the evolution of group after group of new species and genera appear to 
have continued, in certain areas, as around Moffat, for an interval of time of 
incalculable length. Then follows another and lengthy period, during which 
we have perfectly clear evidence, in other areas, of the gradual appearance and 
disappearance of whole families of Coelentera, Brachiopoda, Trilobita, and 
Arthropoda, as well as of other organisms ; and evidently also (although the 
earlier chapters of this part of the history are yet wanting) of the gradual 
evolution of the ancestral forms of the Vertebrata. One of the most interesting 
features in the book is the record of the discovery of fish remains in the higher 
beds of the Silurian Rocks. These fossils have already enabled Dr. Traquair 
to throw a flood of light upon some points that had previously remained in 
obscurity ; and there can be little doubt that we shall shortly learn more still, 
as the beds that yielded these organisms continue to be diligently searched. 
The closing episode of the Silurian Period in Scotland was one in which the 
marine conditions which had so long endured gradually came to an end. 
Continental conditions took the place of oceanic, terrestrial volcanoes arose 
upon what had formerly been the sea-bottom, and the Silurian sea finally gave 
place to the deserts within which the Old Red Sandstone was formed. 
It is chiefly in connection with the eruptive and metamorphic rocks which 
date from this Devonian period, that Mr. Teall’s numerous and valuable contri- 
butions have been given. Like the Stratigraphical and the Palaeontological 
parts of the book this Petrographical part cannot be summarised, for the simple 
reason that, from beginning to end, the work is already as closely condensed as 
it can possibly be. 
Regarding the book as a whole one may confidently state that it is the 
finest geological monograph that has yet appeared, at home or abroad, and 
that it reflects the highest credit upon every one concerned in its production. 
J. G. Ge 
