Bibliographical Notices. 63 



every inspection must be made under a microscope of some sort ; the 

 creatures hide in the moss or blotting-paper, which it is necessary to 

 put into the cell (for they must bo fed and kept damp), and yet they 

 must be examined to see what is going on. . . . Many of them take 

 months to have their changes traced ; indeed I have had a single speci- 

 men alive in the cage for over a year before its changes were complete, 

 so that I might say with certainty to what species the larva or nymph 

 belonged. During this time the cage must be examined every day, 

 and it must be ascertained that the proper hygrometric condition is 

 maintained. ... I have often had fifty such cages in action at one 

 time, each with its inhabitant ; the cages must accompany the 

 observer in every journey, as a few days' neglect would kill all the 

 specimens." It was to Mrs. Michael's " patient attention to them, 

 and to her skilled hand in moving them," that the author owed his 

 " success in rearing them." 



The Oribatidse are vegetable-feeders, of sluggish habits, and " sham 

 dead " in presence of an enemy. Their distribution is probably 

 world-wide: they are found in Spitzbergen as well as in Egypt and 

 Chili ; one from Franz-Joseph Land is identical with our Oribata 

 setosa. In one place — the Land's End — the author detected " what 

 appears to be a local fauna." 



To show how complete the author's treatment of his subject is we 

 may give the headings of the various chapters. The first part con- 

 tains: — (1) Introductory, (2) Terminology, (3) Literature of Oriba- 

 tidaB, (4) Classification of Acarina, (5) Classification of Oribatidas, 

 (6) Development, (7) Habits, (8) Collecting and Preservation, (9) 

 Anatomy of exo-skeleton, (10) Internal Anatomy. The second 

 part is devoted to descriptions of the genera * and species ; but of 

 this we have here only a first instalment, including one half of the 

 genera recognized by the author as represented in Britain. Forty 

 species are described, seven of them as new, while several of the 

 others are discoveries of the author's, previously described b}' him in 

 the ' Journal of the Royal Microscopical Society.' 



The places are admirable works of art, and their accuracy may be 

 depended on, as the figures were nearly all drawn from living 

 examples by the author. There are twenty-two coloured and six 

 plain plates, the latter illustrating chiefly the anatomy. 



We must congratulate the author and the Ray Society very 

 heartily upon the production of this beautiful volume. No such 

 thorough and reliable work has been done anywhere upon any family 

 of that most difficult group the Mites ; and certainly as regards the 

 British species of the group it must be considered as inaugurating a 

 new era. It is to be hoped that the second volume, completing the 

 descriptive portion of the work, will not long delay its appearance, 

 and that the Council of the Ray Society may see their way to furnish 

 us with similar treatises upon other families of the Acarina. 



* The name of one of the genera — Leiosoma — had been previously 

 used, as might be expected, when Nicolet wrote. Hoplophora too, which is 

 retained in the table of genera, had been given to two genera before it 

 was taken up by Koch. 



