REVIEWS 79 
This table shows that of the fourteen species occurring in the Lower 
Silurian of Scotland but one half that number are represented in the 
American Ordovician, the other seven species appearing in the Ameri- 
can Silurian. As most of these species’ occur in the last member of 
the Lower Silurian, the Carodoc, it is probable that this formation 
forms the transition zone between the Ordovician, as we know it, and 
the Silurian. 
The Upper Silurian series is divided into the Llandovery, the 
Tarannon, the Wenlock, the Ludlow, and the Downtonian. ‘These 
formations consist of mudstones, limestones, grits, graywackes, and 
conglomerates. ‘The Downtonian which hitherto has not been recog- 
nized as a part of the Silurian is probably the equivalent of the Water- 
lime formation of our own country. It contains a fauna consisting of 
Ostracoids, Eurypterids, and fishes similar to the fauna of the Water- 
lime formation. This formation immediately underlies the Old Red 
Sandstone. 
, The economic products of the Silurian formations are lead, iron, 
copper, antimony, manganese, zinc, mispickel, silver, and gold, besides 
building materials, road-metal, and hone-stones. 
Other chapters in the book are devoted to contact-metamorphism, 
and to the granites and associated igneous rocks. 
W. N. Loca. 
Genesis of Worlds. By J. H. Hopart BENNETT. Springfield, IIL: 
he WS Nokkers printer, 1O0C; map asA5. 
This work does not need serious review from the point of view of 
science. It is the product of a mind deeply interested in the prob- 
lems of cosmogony and apparently ready to accept the demonstrations 
of science, but yet still under the dominance of the traditional 
anthrophic mode of thought. It betrays throughout a serious lack of 
firm grounding in the elements of the sciences involved in the subjects 
under discussion, a grounding absolutely necessary to their successful 
treatment. The mode and style of the book may be illustrated by the 
following quotation from page 3: 
Inquiring minds have a propensity for tracing things to a first cause, and 
would ask from whence came the great nebula. It could not have sprung 
into existence already formed. It had an origin which is worthy of a most 
careful investigation, for it is one of a class that is represented by thousands 
