TRACHEARl*. 32S 



Etlais, Lat. 

 Chelicerae 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 f . 



LiMNOCHARES, Lat. 



The sucker mouth of the Hydrachnae, but the palpi are simple J. 



Others, — Microphthira, Lat. — are removed from all the rest of the 

 Arachnides by the number of their legs, which only amounts to six. 

 They are all parasitical. 



Caris, Lat. 



A sucker and apparent palpi ; the body rounded, flat, 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., 

 II, pi. xlii. A very common species, in autumn, on grasses and 

 other plants. Having reached the person of the passenger, it 

 climbs up, 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, Hermaim ||. 



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. 

 dytisci, 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. 



* Atax extendens, Fab. ; Miill., IX, 4. 



f Atax geographicm, Fab. ; Miill., VIII, 3, 5 ; At globator, Fab. ; Mull., IX, I. 



X Acarus aquatints, L. ; — Acarus aquaticus holosenceus, De Geer, Insect., VII ; 

 ix, 15, 20 ; — Tromhidium aquaticum, Herm., Mem. Apter. I, ii. 



§ Cans vespertilionis, Lat., Gener. Crust, et Insect. I, 161. 



II Trombidium iiisectomm, Herm., Mem. Apter. I, 16; Ge Geer, Insect., VII, 

 vii, 5; — Tromb. lalirostre, Herm., lb., 15; — Tromb. cornutuin, lb., II, ii ; Tromb. 

 uphidis, lb.; De Geer, Insect., VII, vii, U ; — Tromb. libellula, Herm. lb.; De 

 Geer, lb., VII, 9; — Tromb. culicis, Herm. lb.; De Geer, lb., VII, 12; — Tromb. 

 hipidum, Herm., lb., VII, 7. 



