NOTICES OF BOOKS. xxv 



This book is not intended for the elementary student, nor is it 

 written as a practical laboratory guide, but it is thoroughly suited to the 

 needs of the more advanced students in their second and third years,, 

 and to all those who have some general knowledge of zoology. And 

 further, the inclusion of so large a number of genera, even though many 

 of them are merely mentioned by name (the index covers twenty-seven 

 pages, which gives some idea as to the great number of forms dealt 

 with) makes this work an extremely useful book of reference to all in- 

 terested in Natural History. 



We are glad to see that Prof. Sedgwick has so far omitted the 

 usual introductory chapters dealing with the principles of zoology, these 

 in his translation of Claus' Lehrbuch occupied 181 pages, and conse- 

 quently curtailed the systematic part of the book considerably. We 

 hope Prof. Sedgwick will reconsider his determination to introduce this 

 matter into his second volume, and that he will rather allow his second 

 volume to follow on the lines of his first. When this is complete, let 

 him by all means write us a book on the principles of zoology, for 

 which, we believe, there is great need ; but let it be a book all to itself, 

 the subject being one that is too important to be treated, as is usually 

 its fate, in a few chapters appended to a systematic text-book, which 

 necessitates one or other of the parts being unduly curtailed. 



One short introductory chapter, however, appears to us to be 

 needful, setting forth Prof. Sedgwick's views upon the cell theory. Our 

 author appears to imagine that all students are brought up to believe in 

 the views on this subject which he has so ably maintained in various 

 papers published in the Quarterly Journal of Microscopical Science, and 

 that these views are universally accepted. Hence in his introduction to 

 the Protozoa and Metazoa, he most carefully avoids all mention of the 

 word cell, a state of affairs which, we are afraid, will tend to perplex a 

 great many students, whereas a brief statement of his views on this 

 subject would have saved the student much unnecessary worry besides, 

 bringing clearly before him a very important interpretation of the 

 animal body, which has no doubt in the past been obscured by a too 

 rigid adherence to the cell theory of the older zoologists. 



It is, of course, impossible for one man to be a specialist on every 

 group of animals, and Prof. Sedgwick is to be congratulated on having 

 secured the co-operation of so many able zoologists — to whom he gives 

 due credit in his preface — to assist him in revising special parts of this, 

 work. 



To deal with a few points in detail, we could wish that a little 

 more space had been devoted to the Calcarea among the sponges, as 

 this group so beautifully illustrates the possible lines of evolution of the 

 complex sponge organisation, and especially that a few more figures of 

 the anatomy of these forms had been given, such, for instance, as 

 Leucoselenia, etc., with some reference to Minchin's admirable work on 

 this group. 



The book would be improved by the addition of a few more illus- 



