86 SCIENCE PROGRESS. 



view that the amphibian metamorphosis is recapitulatory is 

 now losing ground. 74 The entire absence of metamor- 

 phosis in the Urodela, and of horny teeth and sucking lips 

 in the tadpole of Xenopus, the wholly aquatic anuran, 

 are formidable difficulties in the way of its acceptation ; 

 and the mind reverts rather to the inner gills and retention 

 of branchial passages by the Derotremata as an infinitely 

 surer mark of the fish. 



Professor Semon's material was accumulated during 

 a two years' sojourn in Australia and the Malay Archi- 

 pelago, and in his prospectus he tells of the acquisition, in 

 additions of embryos and adults, of Monotremes, Marsu- 

 pials and Sirenians, together with members of the leading- 

 classes of the animal kingdom. He has apparently more 

 than covered the ground gone over by our countryman, 

 Caldwell, years ago. While, as Englishmen, we confess 

 to a feeling of bitter regret that the Caldwell collections 

 should have been allowed to remain in oblivion, under 

 the cosmopolitanism of true science, we rejoice in the 

 present prospect, and in the wisdom of Professor Semon's 

 having distributed his material among specialists of recog- 

 nised ability, for immediate investigation. 



Professor Semon's expedition was undertaken at the 

 expense of Dr. Paul von Ritter, who eight years ago en- 

 dowed the Professorship of Phylogeny in the University of 

 Jena, which bears his name, and the spirit of his noble 

 liberality and enterprise is being followed by Gustav 

 Fischer, in the magnificent manner in which the two 

 great treatises before us are being published. It is a 

 matter of sincere congratulation that the University of 

 Jena, which has done so much for the study of the 

 Invertebrata, is now becoming the centre of special work 

 upon the opposite sub-kingdom. 



The monograph is prefaced by a brief account of the 

 expedition, and some general remarks upon the countries 

 visited. In connection with the scheme, Professor Haeckel 

 has written an introductory essay upon the generalities of 

 the Australian fauna. Great, however, as must be the 

 regard in which men of science hold the work of the 



