CLASS IV. ACARI. 133 



Sp. 1. Uro. vegetans. Brown, very smooth, shining. 

 Mitte vegetative. l)e Geer.,vn. 123. pi. 1-fig. 13. 

 Uropoda vegetans. Lair., Leach. 



Inhabits France and England, attaching itself to the legs, abdomen, 

 and elytra of Histeres, Aphodii, &c. by its pedunculated anus. 



Fam. V. CiiEYLETiD.r.. Leach. 

 Ei/es distinct : palpi concealed. 

 Stir PS 1. — Palpi distinct. 



Genus 9. SARCOPTES. Lafreille, Leach. 



Sp. 1. Sar. Scubiei. Subrotundate ; legs short, reddish; four hinder 

 ones, with a very long seta : the plantfc of the four anterior ones 

 terminated by a swelling. 



Mitte de la Gale. Dc Gecr. Acarus Scabiei. Fair. Lc Ciron de la 

 Gale. Geoff'. Sarcopte de la Gale. ImI/-. Hist. Nat. des Crust, et des 

 Iii'iecf. viii. 55. et vii. /)/. 66. Sarcoptes Scabiei. Latr., Leach. 



inhabits the ulcers of the itch. Acarus exulcerans of Linnt is pro- 

 bably this animal, or is at least referable to the same genus. 



Section II. — Legs formed for swimming, 



Fam. Hydrachxad-i. 



Mouth with mandibles. 



Genus 10. HYDRACIIXA. MWll, Oliv., Latr., Leach. 

 Palpi subcylindric, porrcct, arcuate infle.xed, four-jointed, the last acute 



imguiform : mouth produced into a conic rostrum : bod^ globose : 



legs timbriated with hairs, and situated at equal distances from each 



other. 

 Sp. 1. Hi/, geographica. Black, with coGcineous spots and dots. 

 Hydrachna geographica. Mull. Hijdr. 59. tab. 8. fig. 3-5. Latr., 



Leach. 

 Inhabits waters that flow gently. It is a most beautiful animal, and 



is very common near London. 



Genus 11. LIININOCIIAllES. Latr., Leach. 



Palpi incurved, the apex acute simple : jmmlh with a very short ro- 

 strum : bodi/ depressed : legs short, the four hinder ones remote : 

 er/es two. 



Sp. 1. Lim. holosericca. Body ovate, red, rugose, soft; eyes black. 



Acarus aquaticus. Linn. La Tique rouge satinee aquatique. Geoff'. 

 Mitte satinee aquatique. Dc 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 

 varieties of shape,' 



