ORDER TRACHEARLE. 
507 
Ixodes ricinus , Acarus Ricinus, Lin. ; Acarus reduvius, 
D. G. Insect. VII. vi. 1, 2.: of a deep blood-red, with the 
anterior scaly plate deeper, sides of the body edged, a little 
hairy palpi sheathing the sucker. 
Ixodes reticulatus , Latr., Fab. ; Acarus reduvius, Schrank. 
Enum. Insect. Aust. No. 1043, iii. 1, 2 ; Cynorhcestes pictus, 
Hermn. : asli-coloured, with small spots, and small annular 
lines of a reddish brown ; edges of the abdomen striated ; 
palpi almost oval. It attaches itself to oxen, and is, when 
swelled up, five or six lines in length. 
The study of the species of this genus has not been suffi- 
ciently pursued. 
Argas, Lat. Rhyncoprion, Herm ., 
Differ from Ixodes by the inferior situation of the mouth, and 
by the palpi, which do not sheath the sucker ; have a conical 
form, and are composed of four articulations, and not of three, 
as in the preceding genus. 
Ixodes rejlexus , Fab., Lat., Gen., Crust., et insect, &c. 
Of a pale yellowish, with lines of a deep blood-colour, or 
obscure and anastomosed. On pigeons, whose blood it sucks. 
Another species, Argas perricus , described by travellers, 
under the name of the venomous bug of Miana, has been, as 
well as other ixodes, the object of a curious notice, by M. 
Fischer. 
Other Mites, Hydrachnell;e, have still eight feet, but 
ciliate, and adapted for swimming. 
They form the genus HydraCHNA ot Muller, or Athax of 
Fabricius, and live exclusively in the water. Their body is 
generally oval, almost globular, and very soft. That of some 
males is narrowed posteriorly, in a cylindrical manner, or in 
the form of a tail. Their genital parts are placed at its ex- 
tremity ; the female has them under the belly. The number 
