CONTENTS I. Introduction.................. 1 II. Bibliography.................. 4 III. Systematic review................ 8 IV. References..................84 V. Index...................90 I. INTRODUCTION Among the works of acarologists of the past, Berlese's numerous writings take a particular place. Although they contain descriptions of an enormous number of new species, and notwithstanding the fact that they must be regarded as an important contribution to progress of systematics, the way of publishing is superficial to such a degree that Berlese appears to be the author that created the largest number of problems. As a rule his Latin descriptions are extremely short and consist of a few lines only. When exceptionally a figure is given, it represents at most some elementary characters. It even happens that reference is made to a species of which the diagnosis has never been published, whilst on the contrary it also occurs that a species is mentioned two times as new to science. Considering at the same time that it is difficult to recover the dates of publication of many papers, it is clear that reinvestigations are badly needed. Several authors published excellent descriptions of some of Berlese's species, but a review of a group has never been given. Besides, a complete catalogue of the records 1) and a definite bibliography are both still wanting. Because studies of the type-species of genera, and monographs of some groups of primitive Oribatid mites are in course of preparation, a revision of