Bibliographical Notice. 467 



is hardly a reason for retaining a term whicli suggests superficial 

 resemblance only, as if that was the important point ; it is rather 

 a reason for discarding it altogether. We believe that it would 

 have been wiser not to sacrifice strict scientific accuracy even for 

 the sake of a convenient and taking title. 



A useful feature of the present work, which merits com- 

 mendation, is the condensed, but carefully compiled, account of 

 the structural plan which characterizes the leading groups. This 

 is quite sufficieut for its purpose, without being burdened with 

 detail, and will give the student in each case a clear general concep- 

 tion of the form of life which he is about to investigate. There is 

 also a sketch of the classification, in which due account is taken of 

 the later views. In the case of the Polyzoa the system proposed by 

 Mr. Hincks in his ' History ' of the British marine forms is adopted ; 

 but it is to bo regretted that the author has not explained and em- 

 l^hasized the cardinal j)rinciple on which it rests. The only reference 

 to the subject which we have noticed is to be found in the casual 

 remark that "the appearance and arrangement of the zocecia " are 

 " important elements in classification," which certainly throws no 

 light on the distinction between the new method and the old. 



There are special difficulties in the way of framing a natural 

 classification of the Polyzoa, and until very recently systematists 

 contented themselves with one which was admittedly artificial. The 

 suggestive writings of the Swedish zoologist. Prof. Smifct, first indi- 

 cated the direction in which the basis of a more philosophical system 

 must be sought, and formulated the fruitful principle that it is in 

 the zocecial characters rather than in the zoarial — in the essential 

 characters of the cell rather than in the mode of aggregation and 

 habit of growth — that we find the surest clue to natural affinity. 

 The scheme of classification elaborated by Mr. Hincks, and to a largo 

 extent accepted by recent students of the class, rests on this funda- 

 mental principle, which has been confirmed by many new observa- 

 tions, and especially by the evidence obtained of the instability of 

 zoarial habit and the way in which the most marked forms of it are 

 associated indifferently with this or that zocecial type. Few probably 

 would venture to contend that we have yet reached a complete solu- 

 tion of the problem ; but as little can it be questioned that a very 

 considerable advance has been made towards it, and that an immense 

 gain has been realized in the general abandonment of the purely 

 artificial system. In the interest of the student we think that Mr. 

 Pennington would have done well to refer to this very important 

 branch of his subject. 



In the account of the species under the several divisions the dry- 

 ness of mere diagnosis has been relieved by the introduction of many- 

 interesting passages from the writings of Ellis, Johnston, Gosse, 

 Landsborough, and others, and the work has thus been rendered 

 more attractive to those for whom it was originally designed — the 

 young student and the amateur naturalist — though not, we fear, 

 without some sacrifice of its value as a scientific guide. The figures 

 by Mrs. Pennington are for the most part sufficiently distinctive and 



