May 16, 1884.] 
hope ever to change into a lizard. One of the 
greatest steps in evolution was the origin of 
life, but it is unreasonable to suppose that the 
concurrence of favorable conditions necessary 
for this step could occur only once in the his- 
tory of the earth. The impossibility of abio- 
genesis now is, therefore, no argument against 
an abiogenesis once in the early history of the 
earth. 
Again: the author, while he admits that 
evolution is not necessarily destructive of the 
idea of a guiding intelligence in nature, while 
he insists on the necessity of supernatural in- 
terference only at the three points mentioned 
above, thus implying that evolution may possi- 
bly take charge of the process in the interven- 
ing time, yet plainly inclines strongly to the 
supernatural origin of species. Along with 
many other deeply religious minds, he seems to 
shrink from the cordial recognition of the law 
of evolution as if it dispensed with the neces- 
sity of a God in nature. But surely this is 
no more true of evolution than of any other 
law of nature. If the law of gravitation did 
not destroy our belief in a divine sustainer of 
the cosmos, why should the law of evolution 
destroy our belief in a divine Creator? If the 
law of gravitation be nought else than the di- 
vine method of sustentation, then is the law of 
evolution naught else than the divine process 
of creation. 
One thing more: the present epoch is sup- 
posed by the author to differ from all previous 
ones in the fact of rest from creative work. 
We cannot allow that this is the decision of 
science. The very possibility of a science 
of geology is conditioned on the continuance 
of geological changes, i.e., of creative work, 
under our eyes. 
In conclusion, we must say, that, given the 
point of view, the frame of mind of the author, 
—a frame of mind still the most common 
among religious men, — the book is undoubted- 
ly deserving of much praise as the very best 
of its kind. But we feel sure that the frame 
of mind of the religious world is on the eve of 
change, and, with the change, the ‘raison 
d’étre’ of the book will no longer exist. 
TRYON’S CONCHOLOGY. 
Structural and systematic conchology (etc.). By 
GrorGce W. Tryon, jun. Vol. iii. Philadel- 
phia, The author, 1884. 453p.,49pl. 8°. 
Tue final volume of Mr. Tryon’s work has 
appeared, including over four hundred and fifty 
pages of text and about fifty plates. It treats 
of the pulmonate gastropods, the Scaphopoda 
SCIENCE. 
601 
or Dentalia, the lamellibranchs, and the bra- 
chiopods, and contains an appendix with nu- 
merous additions and rectifications and an 
index of genera comprising nearly sixty-five 
hundred different names. We have previously 
referred to what we consider the defects of the 
plan and of some of the details of the earlier 
volumes, — defects which this one shares to a 
certain extent. Nevertheless, as it is in large 
part a treatise on groups which the author has 
made the subject of special study, he has made 
it by far the best of the three, —a fact which it 
gives us pleasure to recognize. In spite of the 
criticism which the work as a whole has seemed 
to us to call for, it is only fair to the author to 
point out the immense labor required to bring 
together the material condensed in the two 
descriptive volumes, and the service which this 
condensation, in spite of certain defects, will 
render to workers in conchology and paleon- 
tology. The devotion with which the author 
has applied himself to the study of mollusks 
for years, has not been fruitless ; and here and 
there in the text most students will find scat- 
tered opinions and remarks which will rec- 
ommend themselves as sound and judicious. 
While the character of the illustrations cannot 
be said to be satisfactory, yet they are in most 
cases sufficiently recognizable to be of service 
to him who knows what he seeks. If we fail to 
find in the systematic arrangement that grasp 
of the subject which might be wished for, and 
that exposition of recently developed truths 
one naturally seeks in the newest book, yet we 
recognize the benefit the author has conferred 
on specialists, at the cost of an enormous 
amount of drudgery, by bringing into reason- 
able orderliness, from innumerable scattered 
sources, the names and descriptions of thou- 
sands of generic forms. For this the work will 
be welcome in many libraries. 
STEAM-ENGINE INDICATORS. 
The Tabor steam-engine indicator. By GrorGE H. 
Barrus, 8.B. New York, 1884. 75p. 24°. 
THE preface of this little handbook states 
that it was prepared at the solicitation of the 
Ashcroft manufacturing company, makers of 
the Tabor indicator, as a book of reference and 
instruction to purchasers and others. 
The subject of principal interest in the book 
is, of course, that of the construction and per- 
formance of the Tabor indicator, especially as 
compared with other indicators ; although there 
is, besides this, a variety of useful matter, 
tables, ete. 
