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Sarcoptes 
of the ambulacral stem, which proves to be a solid rod. The minute seta 
figured by Robin springing from the extremity of the ambulacral stem does 
not I believe exist. The ambulacrum as a whole is the “haftnapf” of Canestrini 
and Kramer. 
The terminal joint of the leg is also armed with two claws. These arise 
from the proximal part of the joint, the one on the dorsal surface, the other 
on the ventral surface. Their shape can be seen in Figs. 7 and 8. Four setae 
also arise from this small and overcrowded joint. The first two (P 7 and P 8) 
are on the mesial aspect of the joint, close to the stiff seta (P 6), similar to it 
in shape, and slightly shorter. The third (P 9) arises close to the base of the 
ambulacral stem on the dorsal side of the leg; it is finely tapered and more 
than twice as long as the ambulacrum. The third (P 10) arises from the 
Fig. 12. Sarcoptes scabiei var. equi. Third and fourth legs of adult female seen ventrally. 
cl, claw; e II1-IV, epimeres of third and fourth legs; H 1-2, setae of hind leg; V 2-^, ventral 
setae; 1-4, leg segments. 
ventro-lateral aspect of the joint. It is about as long as the ambulacrum. The 
terms coxa, trochanter, femur, tibia and tarsus are used by many authors 
when referring to the five joints of the leg. This use is liable to the strong 
objection that the terms are technical names for certain parts of the insect 
leg, with which we cannot homologize the joints of the leg of the mites. As 
it is perfectly easy to speak of the “first joint” or the “fourth joint” I shall 
use this numerical terminology. Robin employs the terms lianche (rotule), 
exingual (trochanter), femoral, jambe, tarse, to designate the five joints. 
The third and fourth pairs of legs (Fig. 12) resemble each other and differ 
from the first two pairs in the following respects; they are inserted as far 
from the middle line as the anterior are, but owing to the width of the body 
at this point they are completely concealed from above; they are smaller 
