TRACHRARI.E. 
321 
) nsfCts, and some of the Coleoptera that feed on cadaverous or excre- 
mentitious substances are frequently covered with them. Tliey have 
even been observed in the brain and eye of man. 
1 he Acari, or Mites as they are vulgarly termed, are oviparous, 
and excessively prolific. Several of them at first have but six legs, 
the remaining two being developed shortly after. Their tarsi ter- 
minate in various ways according to their habits. 
Some Acarides, Lat. — or the Acari proper, have eight legs, 
solely destined for walking, and chelicerae. 
Trombidium, Fah, 
The chelicerae menodactyle, or terminated by a movable hook; 
salient palpi, pointed at the end, with a moveable appendage or spe- 
cies of finger under their extremity; two eyes, each placed on a 
little immoveable pedicle. The body is divided into two parts, the 
first of wliich, or the anterior, is very small, and bears the two first 
pair of legs, together with the eyes and mouth. 
Tromb. holo^ericeum^ Fab.; Herm., Mem. Apter., pi. 1, 2, and 
II, 1. Very common in gardens in the spring; blood-red ; ab- 
domen nearly square, posteriorly narrowed, with an emargina- 
tion ; the back loaded with papillae, hairy at base, and globular 
at the extremity. 
Trovib. tmctorium,Y 2 h. Herm. Apter.; 1,1. Three or four 
times the size of the preceding; it furnishes a red dye. The 
East Indies *. 
Erythr.^us, Lat. 
The chelicerae and palpi of Trombidium; but the eyes are not 
placed on pedicles, neither is the body divided f. 
Gamasus, Lat. Fab. 
Didactyle chelicerae; very distinct or projecting filiform palpi. 
The superior surface of the body, in some, is either wholly or 
partially invested with a scaly skin 
The body is entirely soft in the remainder. Several species of 
this division live on Birds and Quadrupeds. Some are known ; 
such as the 
Gam. ielarius ; Ac. telarius, Fab.; which form extremely fine 
webs on the leaves of several plants, particularly of the Elm, and 
♦ T. fuliginosum, Herm. Mem. Apt. I, .3; — T. bicolor, Ib. II, 2; — T. assimile, 
Ib., 3; T. curfipes, Ib., 4; — T. trigonum, Ib. 5; — T. frimaculatum, Ib., 6. 
•f- Ergthraus jjhalangioides, Lat.; Trombidium phalimgioides, Herm., lb., I, 10; 
— Trombidium quisqnilliarum, Ib., 9; — Tromb. parietinum, Ib., 12; — T. pusillum, 
Ib., 11,4 ; — 7. murorurn, Ib., 5. 
J Gamasus marginafus, Lat. ; Acarus marginatus, Herm., Mem. Apter., YI, 6, found 
on the eorpus callosum of the human brain; — Trombidium longipes, Herm., Ib., 1, 
8; — Aearus coleoptraforv.m, Fab.; De Geer, Mem. Insect., VII, vi, 5 ; — Arams 
?iiru7HUnis, Herm., Ib., 1,13 ; — .4c. vespertilionis, Ib. 14 ; Trombidium hipusiuhdum, Ib., 
II, 10; — Tromb. socium, Ib., II, 13 ; — Tromb. /iliarium, lb., 12; — Tromb. /elarium, 
Ib., 15 : these three species live in society on leaves, covering them with extremely 
fine and silky filaments; — Tromb. celer, Ib., 14 ; — Arams gallintr, De Geer, Insert, 
VII, vi, 13. 
VOL, ni. 
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