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POPULAR SCIENCE REVIEW. 
gentleman’s students during their course of instruction. Hence we may take 
it for granted that Prof. Huxley is pretty well up in everything relating to 
Crayfishes ; and when we consider the position of that type in the series of 
animals, it is easy to understand why our author regards it as specially 
adapted to furnish the text for an * introduction to the Study of Zoology.’ 
In his little volume on the Crayfish just published as one of the 1 Inter- 
national Scientific Series,’ Prof. Huxley describes in the first place the 
natural history, structure, and physiology of that interesting little 
Crustacean, and then proceeds to show what lessons in general zoology may 
be learned by the intelligent application of the special knowledge thus 
acquired. His first chapter is devoted to the natural history of the animal, 
and includes necessarily a general account of its external structure. The 
second and third chapters deal with the physiology of the Crayfish, and 
include the description of its internal anatomy; the fourth treats of the 
morphology and development of the animal ; and the fifth of its comparative 
morphology, its relationship to other living forms, and the general zoological 
teaching to be derived from the consideration of the results of the special 
study of its structure. The line of thought started in this last chapter is 
continued in the sixth and final one, in which the author discusses the dis- 
tribution and aetiology of the group of Crayfishes, and indicates the bearing 
of investigations, such as those to which the previous chapters are devoted, 
upon those higher questions of biological philosophy, the origin of species, 
and the causes of the relationships existing between the members of groups 
of organisms, and between these groups themselves. The whole subject is 
developed in the most admirable manner, and we may fully grant the author’s 
claim on behalf of his book that 1 whoever will follow its pages, crayfish in 
hand, and will try to verify for himself the statements which it contains, 
will find himself brought face to face with all the great zoological questions 
which excite so lively an interest at the present day.’ 
We have yet a w r ord to say about the illustrations, which are numerous, 
well adapted to their purpose, and exceedingly good ; most of the figures of 
Crustacea, and especially those of the Crab and of the species of Lobster, 
are indeed very beautiful specimens of wood-engraving. 
IDE by side with Prof. Huxley’s Monograph on the Crayfish, we may 
notice MM. M* Alpine’s Biological Atlas, as this is to be regarded to a 
great extent as illustrative of another book of which the Professor is part 
author, namely, the Elementary Biology published by him and Mr. II. N. 
Martin in 1875. That excellent little work was in point of fact the outcome 
* Biological Atlas, a Guide to the Practical Study of Plants and Animals, 
adapted to the requirements of the London University , Science and Art 
Department, and for use in Schools and Colleges, 'with Accompanying Text, 
containing arrangement and explanation, equivalent terms, glossary, and 
classifi cation. By D. IVPAlpine and A. N. M‘ Alpine. 4to. W. & A. K. 
Johnston, Edinburgh and London. 1880. 
A BIOLOGICAL ATLAS* 
