Revieics — Prof. Ferd. Roemer’s Lctlicea Palmzoica. 31 
allow of our availing ourselves of mathematical analysis. But if 
this be so, it is better frankly to acknowledge the fact, and not to 
attempt to Support or overthrow a tbeory by a show of numerical 
accuracy, whicli bas no sound basis to rest upon.” This no doubt 
will be a populär sentiment and a flattering unction to many to be 
told, by one of Prof. Green’s ability, tbat tbey who cannot calculate 
are as well off as those who can. But surely Prof. Green will 
acknowledge that in all such cases there are extreme limits, which 
the quantities involved in any problem cannot exceed on one side, 
or fall short of on the other, and thus the application of these to the 
ease in hand involves no “ show of numerical accuracy,” but is an 
honest and a real way of deciding, within the possible limits, whether 
a tbeory be true or false. 
Mr. Croll’s theories of climatal changes are remarkably well 
epitomized in the twelfth chapter, and are evidently favourably 
entertained. Tndeed this twelfth chapter strikes us as much more 
satisfying than the previous one, which treats of the condition ,of 
the earth’s interior. The one subject has been almost as much con- 
troverted as the other, although the latter is the older, and has 
on that aceount had the advantage of being attacked by men of 
the greatest power. Yet it is only lately that Geology has contri- 
buted her share to the data of this great question, and very re- 
cently indeed, if even yet, that physicists have learnt to perceive 
that the facts of geology cannot bend to the results of physical 
inquiry, but that, in order to form a true tbeory, neither can be 
allowed to lord it over the other, and that the requirements of each 
must be equally satisfied. 
A very noticeable and most valuable feature in Prof. Green’s 
work is the abundance of reference to original treatises and papers. 
The book rnight be used as a nearly complete index to the whole 
literature of that part of Geology of which it professes to treat. 
II. — Leth^a Pal-eozoica. By Professor Ferd. Roemer. Atlas of 
62 Plates. Large 8vo. (Stuttgart, 1876.) 
rilHIS Atlas of Plates is the first issued part of a “Lethaea geo- 
_L gnostica,” which, when complete, will cover the entire ground 
of stratigraphical palasontology. The scheme is, on an enlarged and 
improved scale, virtually a new edition of Bronn’s well-known 
work, with the great advantage of having the co-operation of several 
specialists of authority in its production. The Palajozoic portion 
has been placed in the hands of Professor Ferdinand Roemer, of 
Breslau, whose life-long work arnong the fossils of the older rocks 
has been successfully carried on in every part of Europe, and in the 
New World as well as the Old. No choice could be more calculated 
to arouse the highest expectations on the part of geologists and 
palamntologists, and although we have yet before us only the illus- 
trations of the text to come, still there is enough in the brief preface, 
in the choice of fossils, and in the mode of their arrangement, to 
show that the subject is handled by a Veteran whose individuality 
makes itself conspicuous even in such matters as these. 
