163 



done in the future, for "Carpenter" now appears to us to have 

 readied its utmost limit as a one-vohime work. In any future 

 edition a process of reproduction by fission will have to take place, 

 and the "Microscope" and the "Revelations" will have to be 

 issued in two volumes, which should of course be obtainable 

 separately if desired. 



The present edition is printed on much better paper than the 

 last, with the result that the letterpress and the figures in the 

 text are much clearer than before, and the general appearance 

 of the book is now everything that can be desired. D. J. S. 



Das Tierreich. Eine Zusammenstelluug und Kennzeichnung 

 der rezenten Tierformen, 10| x 6| in. Berlin : Friedlander 

 & Sohn. 



Lieferung 3. Oribatidae, by A. D. Michael, xii + 93 

 pages, 15 figures in the text. 1898. Price 6 '80 marks. 



Lieferung 7. Demodicidae and Sarcoptidae. By G. 

 Canestrini and P. Kramer, xvi +193 pages, 31 figures in 

 the text. 1899. Price 12 marks. 



Lieferung 13. Hydrachnidae and Halacartdae. By 

 R. Piersig and H, Lohmann, xviii +336 pages, 87 figures 

 in the text. 1901. Price 21 marks. 



Five years ago the German Zoological Society commenced the 

 truly colossal task of issuing a complete descriptive summary of 

 all the known species of animals. Since that time there have 

 appeared sixteen instalments, and nothing but praise can be 

 bestowed upon the editors and authors alike for the excellent way 

 in which the w^ork has been carried out. The parts which we 

 now have before us deal with various kinds of " mites " — beetle- 

 mites, bee-mites, bird-mites, itch-mites, cheese-mites, water-mites, 

 etc. — and it is the barest truth to say that they are absolutely 

 indisjDensable to those who make the slightest pretension to 

 acquaintance with these little creatures. 



We do not propose to consider in detail each of the parts 

 mentioned above ; but it may nevertheless be useful to some 

 microscopists if, in addition to calling attention to these epoch- 

 making books, we give a few notes on the part dealing with the 

 Hydrachnidae. This has been compiled by Dr. R. Piersig, whose 



