NOTICES OF BOOKS. xv 



into play. The time has passed at which one writer can be expected to 

 produce unaided a well-balanced handbook on all branches of Zoology, 

 and the co-operation of a number of authors for the production of the 

 present treatise alone gives it a claim upon our attention. 



Let it be said at once that as concerning the " Vermes " our fullest 

 anticipations have been realised, that the chapters on Rotifera by Pro- 

 fessor M. Hartog and on Polyzoa by Mr. Harmer are equal in merit to 

 the rest, and that the whole volume is a worthy successor to its im- 

 mediate predecessor on the Insecta — than which no better text-book 

 exists in the English language. 



The volume opens with a scheme of the classification adopted, 

 carefully arranged in tabular form with full-page references to the text, 

 and then follows Mr. Gamble's section on the Platyhelminthes and 

 Mesozoa. The ninety-six pages of this teem with interest and contain 

 many very new and careful observations ; and not the least note- 

 worthy feature of it is the introduction of new figures of rare merit. 

 Figures such as Nos. 5 and 17 both in execution and design are of an 

 entirely new order, and they reflect the highest credit on author, pub- 

 lisher, and all concerned. The inclusion of Frenzel's Salinella and 

 Schulze's Triclioplax among the Mesozoa is perhaps premature, and it 

 were better to have dealt separately with such forms pending confirma- 

 tion and fuller investigation. 



The Nemertinea, Nemathelminthes, and Chaetognatha, are treated 

 in a thoroughly sound elementary manner, although we could have 

 wished for more illustrations of the former. 



It is on turning to the Rotifera, ChcCtopoda, and Hirudinea, that we 

 meet with the greatest novelties and newest treatment. For the first 

 time in his own language, the English student is placed in possession 

 of an adequate account of the structural limitations of the Oligochaeta, 

 Hirudinea, and Rotifera, free of cumbersome detail and embodying those 

 salient facts of structural similarity and dissimilarity upon which alone 

 the inter-relationships of the groups and their position in the scale of 

 animal life can be at all adequately determined. More especially be it 

 noted that the existence among Oligochaetes of female gonads and ducts 

 in a state of organic continuity, and of male pores in front of female, 

 that the development and metamorphosis of the coelom among the Hiru- 

 dinea, together with other features which unite those animals to the 

 Chaetopoda and necessitate the rejection of the time-honoured idea that 

 Leeches arose directly from Platyhelminthes, are luminously set forth 

 by Mr. Beddard. And he gives the student an up-to-date insight 

 into facts of structure and development which in course of prolonged 

 observation have led him and others to the conclusion fast gaining 

 ground that the metamerically recurrent type of nephridium is the 

 more primitive, and that between the diffuse excretory apparatus of 

 certain Chaetopoda and Hirudinea and the Platyhelminthes there may 

 be no close relationship — the latter being perhaps a system sui generis, 

 in which the tubes seek out the primary centres of destructive 



