848 



CLASS V. ARACHNIDA. 



Opilioacarus (Eucarus}, in which the genital pore is pushed forward so as 

 to lie between the coxae of the 3rd pair of legs ; there are but 3 species, O. 

 segmentatus from Algeria, O. italicus from Sicily and O. arabicus from Aden. 



Sub-order 2. CRYPTOSTIGMATA. 



Hard integument, with a continuous dorsal and ventral sclerite ; the stigmata 

 typically open at the base of all the legs, and are concealed in the socket or 

 acetabulum. The cephalothorax bears pseudostigmatic organs ; blind. 



Fam. 2. Oribatidae.* Noiiparasitic, vegetable-eating mites whose 

 hard cuticle has earned them the name of " beetle " mites. Usually found 

 under bark, amongst moss, or lichens and fungi or under stones. A few are 

 aquatic. Pelops with 10 species : Oribata with 4o species : usually in 

 moss, as are the two species of Serrarius ; Zetorchestes 1 species ; Scuto- 

 vertex, Cepheus, Tegeocranus with 5 or 6 species each ; Carabodes and 

 Liacarus with 9 or 10 species ; Notaspis with 26 species ; Amerus with 1 

 species ; Damaeus with 21 species ; Hermannia with 9 species ; Neoliodes 

 and Cymbaeremaeus with 3 or 4 species ; Nothrus with 19 species ; Loh- 

 mannia with 2 species ; Hypochthonius with 5 species ; Hoploderma with 

 eight species ; Phthiracarus with 7 species. 



Sub-order 3. METASTIGMATA. 



Integument mostly hard, tracheae opening by a pair of stigmata above and 

 behind the base of the fourth or fifth or sixth pair of appendages. This sub- 

 order includes the ticks. 



Fam. 3. Gama- 

 sidae. Carnivorous 

 * mites, free on the 



ground or parasitic 

 and then often on 

 Insects, chelicerae 

 chelate, pedipalps 

 free, tarsi two- 

 jointed with a 

 caruncle or suck- 

 ing disk, no eyes, 

 2nd pair of legs 

 often stouter than 

 the others. Gama 

 sus coleoptratorum is 

 often found at 

 tached to the beetle 

 Geotrupes. G. mar- 

 ginatus lives on 

 corpses ; Uropotia. 



this genus attaches itself to beetles by a thread formed of viscid excreta 



from the anus ; Dermanyssus mostly parasitic on birds and bats, D. 



avium infests aviaries and poultry-yards ; Zercon : Piero/itu* lives on bats. 



Fam. 4. Argasidae.f The rostrum is inferior and the mouth parts 



* A. D. Michael, British Oribatidae, Ray Society, 1894, and Das Thier- 

 reich, 3 Lieferung, Oribatidae. 



t Neumann, Revision de la famille des Ixodides, Mem. Soc. Zool. France r 

 viii, 1895 ; x, 1897 ; xii, 1899 ; xiv. 1901. Neumann classes the Argasidae 

 as a sub-family, the Argasinae, which with the sub-family Ixodinae make 

 up the family Ixodidae. 



\ 



FIG. 55Q.Hyalomma aegyptium, Savigny. 

 palpi; c head; d thorax; / abdomen. 



a Chelicerae ; 6 Pedi- 



