TRACHKAni;4^:. 
325 
Eylais, Lai . 
Chelicene terminated by a moveable hook* * * § . 
Hydrachna, Lat. 
The mouth composed of laminae, forming a projecting sucker ; a 
moveable appendage under the extremity of the palpi j-. 
Limnochares, Lat. 
The sucker mouth of the Hydrachnae, but the palpi are simple];. 
Others, — Microphthira, Lat. — are removed from all the rest of the 
Arachnides by the number of their legs, which only amounts to six. 
I’liey are all parasitical. 
Caris, Lat. 
A sucker and apparent palpi ; the body rounded, (lat, and covered 
with a scaly skin§. 
Leptus, Lat. 
A sucker and palpi as in Caris, but the body very soft and ovoid, 
Leptus autumnalis ; Acarus autumnalis , Shaw, Zool. MiscelL, 
IJ, pi. xlii. A very common species, in autumn, on grasses and 
other plants. Having reached the person of the passenger, it 
climbs lip, insinuates itself into his skin at the root of the hairs, 
and occasions an itching as intolerable as that produced by a 
regular itch. It is called the Rouget in France, and in fact it 
is of a reddish colour and very small. 
The remaining species are found on different Insects, and belong 
to the division of the Trombidia hexapoda, Hermann ||. 
Aclysia, Aud. 
The body shaped like a bagpipe, and furnished with a siphon, 
without distinct palpi, situated beneath its anterior extremity, which 
is narrowed, curved and obtuse; very small legs. 
The Aclysiae live on the Dytisci. But a single species — Ac. 
dgtisci, Mem. de la Soc., d’Hist. Nat., I, p. 98, pi. v, fig. 2 — 
was at first known, the one on which M. Victor Audouin esta- 
blished the subgenus. Count Manheiren, a Russian naturalist, 
to whom the science is much indebted for his entomological 
essays, and his readiness to second the efforts of those who 
study it, has, as it appears, discovered another. 
* Afax extendens, Fab. ; Miill., IX, 4. 
-f- Atax yeogruphicus, Fab. ; Midi., VIII, 3, 5 ; At globalur, Fab. ; Miill., IX, I. 
+ Acarus aquaticus, L. ; — Acarus aquaticus holosericeus, De Geer, Insect., VII ; 
ix, 15, 20 ; — Trornbidium aquaticum, Ilenn., Mem. Apter. I, ii. 
§ Cans vespertilionis, Lat., Gener. Crust, et Insect. I, 161. 
11 Trornbidium insectoru/n, Herm., Mem. Apter. I, 16; Ge Geer, Insect., Vi I, 
vii, 5; — Tromb. latirostre, Herm., Ib., 15; — Tromb. cornufuni, Ib., II, ii ; Tromh. 
aphidis, Ib. ; De Geer, Insect., VII, vii, 14; — Tromb. libclhdce, Herm. Ib. ; De 
Geer, Ib., VII, 9 ; — Tromh. culicis, Herm. Ib. ; De Geer, Ib., VII, 12; — Tromb. 
lapidum, Herm., Ib., VII, 7. 
