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family of mites, their distribution and size, and their importance 

 to man from the mischief they frec[iiently do to his property. 

 Surprise, however, will no doubt be expressed at the statement 

 that, although found in all climes in such myriads, the number 

 of known genera does not much exceed fifteen, whilst the number 

 of species is probably less than seventy. Chapter TI. gives an 

 interesting resume of the literature of the subject, from the 

 work of Duares in 1834: to that of Wasmann in 1897. 

 Chapters III. and IV. deal with the classifications of the 

 Acarina and Tyroglyphidae respectively, which have from time 

 to time been proposed by different writers, each in turn being 

 critically examined by the author. Chapter V. will undoubtedly 

 prove of greater interest to the microscopist, treating as it 

 does, in the course of some eighty pages, of the external and 

 internal anatomy of these minute creatures, and being illus- 

 trated by about thirty figures drawn with extreme care under 

 various magnifying powers up to X 800. Chapter VI., 

 which concludes the first part of the book, is devoted to a 

 description of the development and immature stages, the eggs, 

 larvae and nymphs being severally considered, and a detailed 

 record given of observations made during many successful 

 attempts to rear Histioyasier entomojihagus from the nymphal 

 to the adult form. The hypopial stage, as being considered 

 biologically the most interesting feature in the life- history of 

 the Tyroglyphidae, has naturally come in for a large share of 

 the author's attention, and in the course of thirty pages he 

 has not only given us an excellent account of what others have 

 written on the subject, but has largely supplemented this by 

 relating the conclusions arrived at as the result of his own 

 personal observations. In the last hundred pages, which 

 constitute Part II., ]Mr. Michael commences a systematic 

 and exhaustive description of genera and species, beginning 

 with the single species of his own genus Lentungula. Four 

 species of Histiostotna are next considered, and an account of 

 nine species of Glycyphagus brings the present volume to a 

 close, minute details being given as to the structure, life-history 

 and habitat of each, whilst references to the numerous figures 

 given in illustration enable the reader to intelligently follow 

 the descriptions. 



Of the plates, 22 in number, comprising in all 240 figuies, 



