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: 4. The Legs. 
AÅA. General Remarks. 
The legs of the Acari have a different number of joints in 
the different members of the order. It is not always easy to 
identify the number of the joints, as the different authors differ 
with each other with regard to the definition of a joint. Some of 
them consider the part between two grooves as a joint (Kramer); 
according to others (Winkler) a joint must have its own articula- 
tion. The latter opinion is certainly very sensible, sometimes, 
however, it will lead to mistakes, f. inst. in Worneria Canes., if you 
wish to homologize the joints of the different legs, as we will see 
later on. The acarologs differ in their opinions as to the number 
of the joints, and so they do in their interpretations. 
There is another cause to difference of opinion namely the 
so-called epimeron (Michael 10 pag. 16). The epimeron is f. inst. 
very well developed in many Prostigmata; if we have before us 
such an animal as Bdella, no one would hesitate to regard the 
epimeron as a strongly chitinous portion of the sternum; but if we 
regard such a species as A/icus Koch (Berlese 1 Tab. 39) or Caer- 
culus Duf. (1 Tab. 169), and if we remember that the coxae of the 
Opiliones are almost (Opiliones Palpatores Thor) or completely 
(0. Laniatores Thor) immovable, we are obliged to admit that there 
are important evidences of the coxal nature of the epimera. The 
coxae of Eucarus might be named in favour of the same inter- 
pretation. Some acarologs (Brucker) have been of the same 
opinion, others (Michael, Berlese) maintain that the first 
movable joint is the real coxa. 
The legs of the Gamasidae consist of six joints, those of the 
Oribatidae (Michael) of five (6) joints; those of the Zxodidae of six, 
if we regard the epimeron as the first joint. The number of joints 
vary in the different genera of the Prostigmata. The genera Pentha- 
leus and Notophallus Koch have only six joints which most naturally 
might be regarded as coxa (epimeron), trochanter, femur, patella, 
