Les pattes des Acariens en comparaison avec celles des scorpions. Une contribution a l anatomie comparee des Arachnides. - In the present paper the joints (articulations) of the walking-legs in Euscorpiits are compared with those in Opilioacarus (Anactinotrichida) and in Alycus (Actinotrichida) . In this respect the Scorpionida show a doser ressemblance to the Anactinotrichida than to the Actinotrichida. Remarks are made on problems connected with the evolution of the joints and with the homology of the sternal and coxal apophyses of the Arachnidea (it is, e. g., not yet clear whether monocondylic joints derive from bicondylic, or the reverse). In the descriptions of the types of joints, some new terms are introduced, viz. a-, eu-, monobi-, and tridesmatic in order to denote the number of tendon-insertions, at the basis of a segment. The newterm coxapophysis isintroducedhere for the medial apophysis of coxae I and II oftheScorpionida. The coxapophyses could te homologous with the sternapophyses of Phrynichida and Anactinotrichida