786 SCIENCE PROGRESS 



pages of text, and about 1600, in place of 1476, illustrations : the increase being 

 especially noticeable in the case of the sections on Echinodermata and Arthropoda, 

 which respectively show an augmentation of 38 and 45 pages. 



A great change, too, has taken place in the list of specialists responsible for the 

 various sections of this volume ; only three out of the twelve names in the first 

 edition reappearing in the second, namely, those of Messrs. J. M. Clarke, W. H. 

 Dall, and C. Schuchert. In the present edition the number of collaborating 

 specialists is no less than seventeen : the new ones being Messrs. R. S. Bassler, 

 W. T. Caiman, A. H. and H. L. Clark, J. A. Cushman, A. Handlirsch, R. T. 

 Jackson, A. Petrunkevitch, P. E. Raymond, R, Ruedemann, J. P. Smith, F. Springer, 

 T. W. Vaughan, and C. D. Walcott. A better and more representative list it 

 would be difficult to bring together ; each specialist being eminent in his own 

 particular department. 



Such a sweeping change in the staff, coupled with the increase in the bulk of 

 the volume, implies of course equally radical changes in the text ; so that, as the 

 editor remarks in his preface, the work can no longer be properly styled Zittel's 

 Text-Book, as it is in effect a composite production, although still modelled on 

 the lines of the famous German original. Apart from the importation of new 

 blood, such additions and alterations were inevitable, as invertebrate palaeontology 

 has not been standing still during the first dozen years of the present century ; 

 and, as a matter of fact — to quote the editor's own words — " many parts of the 

 work have been entirely rewritten, others have been emended, rearranged, and 

 enlarged, and the classification in various places has been very considerably 

 altered." 



The main groups, however, stand practically as they were in the first edition, 

 the only alteration being that the Echinodermata and the Vermes have changed 

 places, the latter coming first, instead of second, in the present edition. 



In regard to these (seven) main groups, the noticeable feature is the inclusion 

 (as in the first edition) of the Porifera (sponges) in the Ccelenterata ; and since this 

 arrangement differs from that adopted by the majority of zoological writers, it 

 would have been well, we think, if the reasons for the departure from the usual 

 practice had been stated in detail, instead of the reader being left to find them out 

 as best he may. It of course involves a considerable change in the usual defini- 

 tion of the Ccelenterata — a change which is not, in our opinion, on the side of 

 simplicity and clearness. 



Extreme technicality, it need scarcely be mentioned, is the leading character of 

 the work, which is intended solely for more or less advanced students, and for 

 palaeontologists desirous of information with regard to groups which do not form 

 the subject of their special studies. It is not, however, to palaeontologists alone 

 that the work should appeal, for it contains much valuable information with regard 

 to certain existing species, notably the nautilus ; and if it be thereby the means 

 of inducing zoologists — in the restricted sense of that term — to devote more 

 attention (in some cases we may say to devote any) to palaeontology than is 

 the practice with many, it will have done good service in helping to place 

 biology on a broader and more philosophical basis. 



The excellence and number of the illustrations form an especially valuable 

 feature of the volume ; among those worthy of special commendation being the 

 figures of Palaeozoic insects, crustaceans, arachnids, and other arthropods, which will 

 come as a revelation to those who have not hitherto devoted attention to this part of 

 the subject. Most wonderful of all these Palaeozoic insects are the giant dragon- 

 flies of the Upper Carboniferous, which are regarded as forming a group — the 



