THE AC ARID A. 
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mite belonging to the genus Dermanyssus lives upon it as a 
parasite, and also undergoes a metamorphosis, and the larva is 
six-legged. 
Another spider with tracheae and an unsegmented abdomen 
appears to have a metamorphosis after having attained adult age, 
besides those which occur previously. Rhyncholophus cenereus is 
common in the environs of Montpellier, where numerous colonies 
of it may be found in shady places by the roadside. It is a small 
spider not more than a line in length, but its long legs give it an 
important appearance, and enable it to run and spring actively. 
There are four red eyes in two groups, one on each side of the 
front of the body, which is more or less square shaped, and 
the dingy colour of the delicate but closely-set hairs gives the 
specific name. It has a long and sharp beak-shaped mouth, and 
lives upon the juices of other insects. 
After having obtained its eight legs, and apparently its adult 
stage, a metamorphosis takes place, for immobile nymphs are 
found in holes and under stones, clothed with the exuviae of the 
supposed mature spider, and the eight legs and hairy tissues can 
be readily examined. 
Small creatures come forth from this second nymph condition, 
which resemble those just noticed ; but they are less round in 
shape, less red, and are able to reproduce their kind by eggs. 
The garden unites belonging to the genus Trombidion are often 
of a fine red colour, and one of them chooses such a dangerous 
host to be parasitic upon as the active running wall spider. The 
mite frequents the female spiders especially, and fixes itself upon 
the hind thighs; for, unlike the males, they have short palpi, 
which cannot reach these parts, so that the parasites live there in 
security. The males soon pull the mites off if they settle upon 
them. When full-grown these mites are as large as a mustard 
seed, and they have oval-shaped bodies, which are swollen, slightly 
hairy ; and have two eyes. But there are only six legs, which are 
short, but nevertheless useful and sufficiently strong to enable 
the mite to change its position. 
When the larva — for such is the mite — detaches itself from 
its spider host, it seeks the ground, and hides up in small dark 
holes, becomes motionless, and remains so for twenty days. 
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