324 ARACUNIDES. 
Huntsmen in France call the species which attaches itself to the 
Dog, Louvette. It is the 
Ixodes ricinus ; Acarus ricinus, L.; Acai’us reduvius, DeGeer, 
Insect., VII, vi, I, 2. A deep blood-red; the sealy, anterior 
plate still darker; sides of the body turned up, and slightly 
hairy; palpi forming a sheath to the sucker. 
Ixodes reticulatus, Lat. Fab.; Acarus reduvius, Schrank, 
Enum. Insect., Aust., No. 1043, iii, 1,2: Cynorhfestes pictus, 
Herm. Cinerous, with small reddish-brown spots, and little 
annular lines of the same colour ; edges of the abdomen striate; 
palpi nearly oval. It infests Oxen, and when tumefied, is six 
lines in length. 
The species of this genus have not been sufficiently studied *. 
Argas, Lat . — Rhynchoprion, Hei'm. 
Distinguished from Ixodes by the inferior situation of the mouth, 
and by the palpi which do not encase the sucker, have a conical 
form, and are composed of four joints, and not of three, as in the 
preceding genus. 
Argas reft exits; Ixodes refl exits, Fab.; Lat. Gen. Crust, et 
Insect., I, vi, 3, Herm. Mem. Apt. IV, 10, 11. Pale yellow, 
with dark blood-coloured, or obscure and anastomosing lines. — 
On Pigeons. 
Argas persicus ; Malleh de Mianeh. This species, described 
by travellers under the name of Punaise venimeuse de Miana, 
with other Ixodes, constitutes the subject of some curious obser- 
vations published by M. Gotthef Fischer de Waldheim. 
Others again — HydrachnelLjE, Lat. — have also eight legs, but 
they are ciliated and adapted to natation. 
They form the Genus Hydrachna of Muller f or ihai oi Athax 
Fab., and are wholly aquatic. Their body is generally oval or nearly 
globular, and very soft. That of some males is narrowed posteriorly, 
so as to resemble a kind of tail, their genital organs being placed at 
its extremity ; in the female, they are on the inferior surface of the 
abdomen. The number of eyes varies from two to four, or, accord- 
ing to Muller, even to six. 
The mouth of those species, I have been able to study, offered the 
three following modifications, which have served as a base to three 
generic divisions, but to which it is almost impossible to refer all 
Muller’s species of Hydrachnse, that naturalist not having described 
them with sufficient minuteness. 
* Acarus (egyptius, Ij. -, Herm. Mem. Apter., IV, 9 ; L. IV, 13; — Acarus rhino - 
cerotis, De Geer, Insect., VII, xxxviii, 5. 6 ; — Acarus americanus, L. ; — Ac. nigua, 
De Geer, Ib., XXVII, 9, 13. See the genus Ixodes of Fabricius, and the work of 
Leach on ihe apterous Insects of Linnaeus — Trans. Lin. Soc., XI. 
f Hydrachnn, Herm. 
