XVI SCIENCE PROGRESS. 



metabolism, much as do the trachea: of Insects. More might perhaps 

 have been said concerning the Hmits of modification and development 

 of the chaetiparous system, and it is not a little remarkable that Mr. 

 Beddard should have omitted reference to the larval sensory apparatus 

 oi Acanthodrilns which he himself discovered. 



Dr. Benham's chapter opens with a sufficiently detailed and guarded 

 account of DiitopJiiliis, Polygordins, and Poiitodrilus, classified together 

 as the Archiannelida. He then passes on to the Polycheeta, and gives 

 us a succinct account of their structure, development, and life history, 

 with ample allusion to habits — especially as related to peculiar morpho- 

 logical adaptations. We note with much satisfaction the incorpor- 

 ation of the very careful and praiseworthy observations of Watson upon 

 tube-formation, of the like of which we cannot have too many in these 

 days of reckless generalisation upon wholly morphological characters. 

 Asexual reproduction is adequately treated, the wonderful Sjllis raiiiosa 

 and Eunice tibiana find appropriate places in the text, and, as with 

 other sections of the work, coloration, luminosity, and regeneration, 

 are in due course considered. Distribution and palaeontology come in 

 for due notice, not altogether with the novelty which characterises the 

 work of other contributors to the volume, however, for the paragraph 

 on the " palaeontology " of the Nemertines is worthy that so notorious 

 on Snakes in Iceland. Better and more numerous illustrations appear 

 to us desirable for this portion of the work, especially as delineating 

 the "Trochosphere" larva. That given (fig. 145) is exceedingly poor, 

 and even the familiar " Loven's larva" series of earlier text-book writers 

 would be welcome. 



Concerning phosphorescence, we are pleased to note that the 

 author of the chapter on the Oligochaeta omits all reference to the 

 paper by Secchi, cited in his "Monograph of the order Oligochaeta" 

 to which he frequentl}' alludes, for it in no way deals with Earth- 

 worms. 



For the two concluding chapters by the Editors we have nought 

 but praise. Their well-known researches during the last decade upon 

 groups of animals dealt with in this volume led us to anticipate success, 

 and they have not disappointed us. Novelties like the discovery of the 

 Nemathelminthes Arhynchidie, and careful observations like those upon 

 the processes of budding and reproduction among the Polyzoa, are now 

 seen to have been related to a laborious piece of work on the student's 

 behalf, for which it is difficult to adequately return thanks. We are 

 especially grateful to Mr. Harmer, whose pages of the book are a fitting 

 corollary of his well-known monographs, which have always appeared 

 to us of equally high literary and scientific merit. 



Mr. Harmer deals by preference with the British Polyzoa, and 

 gives a valuable key to their identification ; but we do not consider 

 this sufficient justification for omission of all mention of the arenaceous 

 Polyzoon Cryptozooii discovered by Bracebridge Wilson and described 

 by Dendy from the Australian seas, and of genera so remarkable as 



