1 
230 The Irish Naturalist October, 
REVIEWS. 
THE NEW " THOMSON," \ 
Outlines of ZooIog:y. By J. Arthur Thomson, M.A. 4th editiou, 
revised aud enlarged. Pp. XX.+856. Edinburgh and Loudon : 
Young J. Pentland, 1906. Price, 15^. 
The issue of another edition of Prof. Thomson's well-known text-book 1 
is sufficient evidence of its continuous popularity, and shows at the same j 
time that the author will spare no pains to make his work merit the warm j 
approval of students and teachers of zoology. In this edition 36 pages of 
letterpress and 55 new illustrations have been added. The accounts of \ 
the Tunicates and of Balanoglossus and other worm-like animals, now ; 
regarded as low type vertebrata, are fuller than in previous editions. In 
the chapter on the Protozoa there is now a summary of Schaudinn's re- 
searches into the life-history of coccidiau parasites, but fuller references ^ 
to the Haemosporidia that cause blood-diseases in man and domestic j 
animals would have been welcome. The Fishes are classified according | 
to the views of most recent authorities on the class, but the chapter on ^ 
Mammalia — excellent and full of information as it is — needs further re- ■ 
vision. For the Okapi, and the recently discovered fossil Hyracoidea | 
and ancestral Proboscidea are all treated as non-existent. We notice, ^ 
too, that Prof. Thomson retains the old division of the Streptoneurous \ 
Gastropoda into Zygobranchs and Azygobranchs, which has been 
abandoned by modern malacologists. The section on the Arthropoda ; 
is exceptionally good. In the next edition we hope that the author will \ 
see his way to abolish the class " myriapoda," and treat centipedes and • 
millipedes as separate classes. The figures of these these two types, by ] 
the way, are among the few bad things in the book ; another figure that 
we hope may soon be replaced is that of the arterial system of the pigeon j 
on p. 644. I 
In the domain of biological theory there are not a few improvements. j 
A short summary of Mendel's observations has been added, but the ] 
deductions drawn thence as to the nature of the germ-cells is curiously \ 
omitted. We wonder what the Mendelians will think of the '* Diagram 1 
showing hypothetically the action of natural selection in the evolution ! 
of a white race of mice from a dark-coloured stock'' on p. 811! But | 
whatever our opinion on matters of detail, the book as a whole is one to \ 
be confidently recommended to students. For the subject is made so j 
*' living," the facts mentioned are so used to point out problems that i 
remain for solution, the need for fresh observation and experiment is so 
constantly urged, that no student who uses the book intelligently can j 
fall into that most dangerous mistake of believing in the infallibility of 
any printed page 1 ' 
G. H. C. j 
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