132 MODERN SYSTEM. 



Acarus geniculatus* Linn. 



Inhabits trees and beneath stones. It is common in Sweden, Ger- 

 many, and England. 



Genus 5. NOTASPTS. Hermann. 



Bodt/ covered I)y a coriaceous skin, tlie anterior part rostrated, the pro- 

 duced part inclosing the organs of mastication : ulnhmicn subglobose, 

 the sides anteriorly with a wing-like process: tarsi with claws. 



Sp. 1. Not. hu)nc?'alis. Abdomen blackish-chesnut; the produced i)arts 

 membranaceous. 



Mitte a rebord. De Geer. Oribita humeralis. Latr., Leach. 



Inhabits moss and beneath stones. It is not unconimon in the southern 

 parts of Devonshire. 



Genus 6. ACARITS of authors. 



Bodt/ soft : mouth naked : tarsi with a pedunculated vesicle at their ex- 

 tremities. 



Sp. 1 . ^Ica. domesticus. White, with two brown spots ; body ovate, the 

 middle coarctatc, with very long hairs: legs equal. 



Acarus Siro. Linn., Fain-., I^each Edin. Enci/cl. vii. 41.5. Acarus do- 

 mesticus. Latr., Lcaeh Supp. to Eniycl. Brit. i. 111. 



Inhalnts houses, living in cheese and flour that have licen kept too 

 long. 



B. ]\L)uth furnished nitit a rostrum. 



Fam. I\'. I.xoDiAD^;. Leach. 

 Ej/cs obscure or concealed. 



Stirps. 1. — Pdljii and rostrum exserted. 



Genus 7. IXODES. Latreille, Leach. Cynoeikestes. Hermann. 



Palpi equally broad, longer than broad. 



Sp. 1. Ix. llicinus. Scutum rounded, smaller; with the vagina of the 

 rostrum and the legs tiiscous : al)domen varying in colour. 



Acarus Ricinus. Linn., Fabr. Ixodes Ricinus. Latr., Leach. 



Inhabits Europe, attaching itself to dogs. In Britain it is called the 

 D Oil-tick. 



Dr. Leach has written a paper on the British species of this ge- 

 nus, which is ])iiblishcd in the eleventh volume of the Transactions 

 of the Linnean Societi/. 



Stirps 2. — Palpi and rostrum hidden. 



Genus 8. UROPODA. Latreille, Leach. 

 Body oval, orbiculate : back corneous, clypeiform, the disc being gra- 

 dually convex; beneath flat: anus produced into a long filiform pe- 

 dmicle (by which it adheres to coleopterous insects) : legs very short, 

 pressed close to the body, the first pair shortest, the second pair 

 rather longer, the third distinctly longer, the fourth pair longest. 



