ORDER TRACHEARIiE. 
503 
that of the itch. It appears to result from the experiments of 
Dr. Gales, that the mites of the human itch, placed upon the 
body of a sound person, will inoculate him with the virus of 
this malady. We also find various sorts of mites on insects, 
and many coleoptera which live on cadaverous or excremen- 
titious substances, are sometimes altogether covered by them. 
They have been observed even in the brain and the eyes of man. 
The mites are oviparous, and multiply exceedingly. Many 
are born with only six feet, and the other two are developed a 
little time after. Their tarsi are terminated in various ways, 
and appropriate to their habits. 
Some (Ac A rides proper) have eight feet, exclusively 
adapted for running, and forceps. 
Trombidium, Fab., 
Which have the forceps talon-like, or terminated by a mobile 
hook; projecting palpi, pointed at the end, with a mobile 
appendage, or sort of claw, under their extremity ; two eyes, 
situated each at the end of a small fixed pedicle, and the 
body divided into two parts, of which the first or anterior is 
very small, and carries, besides the eyes and mouth, the first 
two pair of feet. 
T. holosericeum , Fab., Hermn., Mem. Apt. pi. i. 2. and ii. 
1. Very common in spring in gardens ; of a blood-red ; the 
abdomen almost square, narrowed behind, with an emargina- 
tion ; the back charged with papilla3, hairy at their base, and 
globular at their extremity. 
Another species is found in the East Indies, three or four 
times larger, and which yields a red tincture. (T. tinctorium , 
Fab.) Herm. Mem. Apt. I. i. 4. 
Erythrasus, Latr ., 
Which have the forceps and palpi of Trombidium , but the 
eyes are not carried on a pedicle, and the body is not divided. 
