48 A. e. OUDEMANS, NOTES ON ACARI. 



Then we observe that in the old classification, followed in 

 »das J Tierreich» many genera contain heterogenic species. 

 1 think we wust draw more attention to the epimera I. If of 

 a certain genus the type -species has free epimera I, no species 

 with joined epimera should be placed in the same genus. 

 E. g. the type-species of the genus Dermoglyphiis Mégn. : 

 D. elongatiis (Mégn.), has free epimera 1; now most of the 

 species of Dermoglyplms Mégn., described afterward, are provided 

 with epimera I joined to a rather long sternum. This is a 

 mis-take which gradually raust be redressed. 



It is a singular custom to form groups (genera, subgenera, 

 subfamilies, etc.), basing on the particularities of the males, 

 e. g. their being provided with deeply incised abdomen, or 

 not, their having thick legs III, or IV, or both, etc. I think 

 we have erred in doing so. If we observe the 5 stades of 

 development of the different species, we are struck by the 

 following facts. If a larva has free epimera I, the nymphs 

 generally have also free epimera I, but the adults may be 

 provided with joined epimera. This proves, that free epimera I 

 are more primitive than joined ones. If a larva shows joined 

 epimera I, the subsequent stades are always provided with 

 joined epimera I, never with free ones. This proves that species, 

 genera, subfamilies with joined epimera I are of earlier date 

 than those with free epimera. 



It is a fact that several so-called species of Analges Nitzsch 

 have enormously varying males, whilst their females are 

 equal to one another like two peas. Also the females gene- 

 rallv equal the deutonymphs so closely, that only the presence 

 of the genital apparatus proves the difference between the 

 deutonymphae and the females. These two facts prove that 

 the females have kept the more primitive shape and that the 

 males vary according to circumstances. Eustathia cultrifera 

 (Rob.) and Chauliacia sècarigera (Rob), live both on Apus apus (L.); 

 their females vary considerably, but their males show the 



