Since 1964 I have been publishing a series of extensive descriptions and morphological studies of various groups of mites. Although this type of work is rather time-devouring, it enlarges our knowledge considerably as to structures hitherto generally neglected. At the same time, however, we must not lose our broader view on the Acarida as a whole: the analytical investigations should be supplemented by synthetic work. For this reason, I used to add to my descriptions a number of remarks on subjects of general importance. It now appears that this way of publishing does not keep pace with the development of my views. A number of stray observations and opinions did not come off, and had to wait a long time before being included in an appropriate study. For this reason, the present series of notes is started, which has the advantage that it can be composed in restricted spaces of time, and which is meant to fill up the gaps left by the larger studies. The first part of the series, which is published here, deals already with various subjects; these subjects relate to practically al orders of mites. A. PRELIMINARY REDESCRIPTION OF ALLOTHYRUS CONSTRICTUS (DOMROW) In 1961, in a study of the Holothyrida, I created the genus Allothyrus with Holothyrus constrictus Domrow as type. Although at that time I had not yet seen the species, the original description sufficiently demonstrated its separate systematic position. In a survey of relationships and differences between Opilioacarida, Holothyrida, and Gamasida (Van der Hammen, 1966), I pointed to the necessity of a redescription of the type-species of Allothyrus, because several important characters of this interesting genus were still unknown. Shortly afterwards, Dr. R. Domrow (Queensland In-