132 MODERN SYSTEM. 



Acarus geniculatur?. Lin?i. 



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

 many, and England. 



Genus 3. NOTASPIS. Hermann. 



Body covered by a coriaceous skin, the anterior ])art rostrated, the pro- 

 duced part inclosing the organs of mastication : abdomen subglobose, 

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



Sp. 1. Not. humeral is. Abdomen blackish-chcsnut; the produced parts 

 membranaceous. 



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



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

 parts of Devonshire. 



Genus 6. ACARUS of aidhors. 



Body soft : vwuth naked : ta?'si with a pedunculated vesicle at their ex- 

 tremities. 



Sp. 1. Aca. domesticns. White, with two brown spots; body ovate, the 

 middle coarctate, with very long hairs : legs equal. 



Acarus Siro. Linn., Fabr., Leach Edin. Enci/cl. vii. 415. Acarus do- 

 mesticns. Latr., Leach Supp. to Enri/c/. Bril. i. 4i4. 



Inhabits houses, living in cheese and flour that have been kept too 

 long. 



B. j\louth furnished with a rostrum. 



Fam. IV. IxoDiAD.TE. Lcttch. 

 Eyes obscure or concealed. 

 Stirps. 1. — Palpi and rostrum exsertcd. 



Genus 7. IXODES. Latreille, Leach. CynorhcesTtes. Hermamt. 

 Palpi equally l)road, longer than broad. 

 Sp. 1. Ij-. Ricinns. Scutum rounded, smaller; with the vagina of the 



rostrum and the legs fuscous : abdomen varying in colour. 

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

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

 Dog-tick. 



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

 nus, which is published in the eleventh volume of the Transactions 

 of the Linnean Society. 



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- 

 duncle (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. 



