CLASS IV. ACAKI. 
1S3 
Sp. 1. Tiro, vegetans. Brown, very smooth, shining, 
hlitte vegetative. De Geer., vii. 123. pi. 7 -fig' 13. 
Uropoda vegetans. Lair., Isach. 
inhabits France and England, attaching itself to the legs, abdomen, 
and elytra of Histeres, Aphodii, &c. by its pedunculated anus, 
Fam. V. Cueyletidje. Leach. 
Eyes distinct : palpi concealed, 
Sttiips 1 . — Palpi distinct. 
Genus 9. SAUCOPTES. Latrcille, Leach. 
Sp. 1. Sar. Scabies. Subrotundate ; legs short, reddish; four hinder 
ones, with a very long seta : the plant® of the four anterior ones 
. terminated bv a swelling. . . _ , _. , , 
•Mitte de la Gale. De Geer. Acarus Scabiei. Fair. Le Ciron de la 
Gale. Geoff. Sarcopte de la Gale. Lair. Hist. Nat. des Crust, et des 
Insect, viii. 55. et vii. pi. 06. Sarcoptes Scabiei. Latr., Leach. 
Inhabits the ulcers of the itch. Acarus exulcerans of Lime is pro- 
bably this animal, or is at least referable to the same genus. 
Section II.— Legs formed for swimming , 
Fam. Hyi)uachkac.e. 
Mouth with mandibles. 
Genus 10. HYDRACHNA. Mull., Oliv., Latr. Leach. 
Palpi subcylindric, porrect, arcuate indexed, four-jointed, the last acute 
unguiform: mouth produced into a conic rostrum: Wy globose . 
legs fimbriated with hairs, and situated at equal distances from each 
C hC W geosraphica. Black, with coccincous spots and dots. 
%drachna geographic® Mull. Hydr. 59. tab. 8. fig. 3-5. Latr., 
Inhabits" waters that (low gently. It is a most beautiful animal, and 
is very common near London. 
Genus 11. EIMNOCHARES. Latr., Leach. 
Palpi incurved, die apex acute simple: mouth with a very short ro- 
strum : body depressed : legs short, the four hinder ones remote , 
Sp-T Li m. holosericea. Body ovate, red, rugose, soft; eyes black. ^ 
Acarus aquaticus Linn. La Tique rouge satmee aquatique. Oeojf. 
Mitte satinee aquatique. De Geer. Trombidium aquaticum. Fabr. 
Limnochares holosericea. Latr., Leach. . 
Inhabits Europe. It is very common in most of our ponds during the 
summer months. It varies much in colour, but is generally found 
of a bright red or greyish-red colour, and of all the intermediate 
v arieties of shape. 
