38 THE ZOOLOGIST. 
A concise manual which obviates the necessity of taking down 
numerous books to the sea-side will always be valuable and © 
popular, especially since the cost of anything approaching to a 
complete set of monographs is prohibitory to the great majority 
of field-naturalists. As Mr. Pennington’s work is designed for 
this purpose, and is not intended to be merely a ‘popular’ book, 
it merits a careful scrutiny, as we have now arrived at a time 
when it is eminently desirable and comparatively easy to be 
perfectly accurate in structural details and in zoological nomen- 
clature. 
No practical naturalist will object to the title of the 
book or to the inclusion of the Polyzoa, but the omissions will 
lay the author open to some degree of criticism, since he states 
in the Preface he has ‘‘ endeavoured to make the work a complete 
guide to all known British species.” 
The work commences with an interesting historical sketch, 
and general remarks on classification and distribution. The 
definitions of the groups of Hydrozoa and Actinozoa are un- 
satisfactory from the modern standpoint, and there are details of 
classification, as in the latter group, to which exception might be 
taken. Few zoologists now admit the Polyzoa into the sub- 
- kingdom Mollusca; their nearest allies are certainly the Gephyrea, 
and Mr. Pennington should have referred his readers to Prof. 
Lankesteyr’s article, ‘‘ Polyzoa,” in the ‘ Encyclopedia Britannica.’ 
Before dealing with the systematic portion, Mr. Pennington 
gives a useful and on the whole an accurate summary of the 
anatomy of each group. The obsolete diagram of the Hydra 
(pl. i., fig. 1) should have given place to one which would really 
illustrate the text. The ectoderm and endoderm should be repre- 
sented as distinct layers, and the generative glands are hopelessly 
erroneous. Prof. Lankester’s article on the Hydrozoa (Encycel. 
Brit.) does not appear to have been sufficiently carefully studied. 
The discovery of nerve-cells in Hydroids by Weissmann and Von 
Lendenfeld is not mentioned. 
The use of the term ‘“‘ stomach” in dealing with the anatomy 
of the Alcyonaria is somewhat obscure, as it might lead the 
reader to expect a tube or sac comparable with the stomach of 
other animals. The csophagus is correctly stated in the account 
of the Actiniz to be lined with ectoderm, but the reader is left to 
assume this for the Aleyonaria. The cesophagus is stated to lead 
