1898J SOME NEW BOOKS 201 



zoology, it is probably the I)est suited for the purpose. After all, 

 it is the plan followed in a general course of lectures on zoology, 

 and the book becomes to some extent useful in the laboratory. 

 ]jut we wish that a greater uniformity liad prevailed in the way 

 in whicli the plan is carried out ; for whilst in most cases, such as the 

 Vertebrata, Arthropoda, Mollusca, a few representative genera are 

 mentioned under each of the small divisions of the class, in other 

 groups, e.g., Annulal;;. Echinoderma, Coelentera, these are omitted, 

 and the student will lind it impossible to locate the various genera 

 mentioned in the subsequent account of the general structure of the 

 group as exhibituig modifications in this or that organ, as compared 

 with the type. 



Again, it would have added very considerably to the value and 

 interest of the book, both to English and to Australasian students, if 

 there had been unifdrmity in the plan of stating whether the 'ex- 

 ample ' is a Northern or a Southern form. 



For instance, Pctromyzon is taken as the type of the Cyclostomi ; 

 but we are told, in the opening sentence, that it is a Northern form, and 

 is represented in the Southern hemisphere by Geotria and Mordacia. 

 In the case of Astacus, however, we are merely informed that it is 

 represented in the South by allied genera ; but the fact that Para- 

 iiephrops is the New Zealand genus is only mentioned in the chapter 

 on geographical distribution at the end of voL ii. [It may be noted 

 that Paranephro2:)s and Asthenosoma, and some other genera men- 

 tioned in the text, are not to be found in the index.] But in the 

 Annulata and Echinoderma no indication is given as to whether the 

 type occurs in Australasia or not ; there is nothing in the immediate 

 text to show that Lmnhricus, the type, is represented by Acantltodrilus 

 in New Zealand. 



The classification adopted will, perhaps, scarcely satisfy specialists 

 in the various groups ; nevertheless, there is much to be said against 

 the tendency, so frequent at the present day, of introducing new 

 ' systems ' into books which are, after all, intended as a guide to 

 students. These new classifications are really stumbling-blocks to a 

 beginner, for in reading, as he should do, other text-books or 

 zoological classics, he will meet with different systems which he 

 has not sufficient knowledge to co-ordinate with the more modern 

 one which he has recently read. Moreover, the beginner is unaware 

 of the instability of ' systems,' and naturally thinks that the facts of 

 the science being firmly established (as he believes), the deductions 

 from these facts should be stable also. Nevertheless, there comes a 

 time when a rearrangement must be made, and such a sub-divisiou 

 as that of the Crinoidea into Neo- and Palaeo-crinoidea should be 

 given up. So, too, the groups ' Myriapoda ' and ' Gephyrea ' ought 

 to be split up, and the forms hitherto included distributed to 

 their proper places. 



"We are glad that the authors refuse to see in the Polyclad 

 Turbellarians any close relationship with the Ctenophora, but 

 rightly place the Ehabdocoelidn at the base of the class, and 

 recognise that Ctmoplana and Coeloplana are merely slightly 

 modified Ctenophores. 



Dinophilus is placed with the Eotif era and Gastrotricha, as a phylum 



