338 THE MICROSCOPIST. 



Class Arachnidce. Air-breathing. Head and thorax 

 blended. No feelers. Two pairs of jaws and legs. Ab- 

 domen without members. Sexes distinct. 



Order Linguatulidce (Pentastomidee). Worm-shaped, 

 ringed. Mouth rounded, with horny border. Four legs, 

 hooklike and sheathed. Surface hard and pierced by 

 stigmata. Metamorphosis complete. 



30. Pentastomum Tcenioides. Inhabits the nasal cavities 

 of the dog and wolf. The larva have been found in man. 



31. Pentastomum Denticulatum. Encapsuled, curved, 

 calcified. On the surface of the liver, etc. 



Order Acarince. Mites. Body compact, inarticulate. 

 Mouth for biting, sucking, or stinging. Respiration by 

 tracheae. 



Family Dermatophili. Hair-follicle rnite. Elongated. 

 Worm-shaped, fringed abdomen. Suckers and stiletto- 

 shaped jaws. Four pairs of short bipartite feet. 



32. Acarus Folliculorum (Dermodex Folliculorum). 

 Found often in ear-wax and sebaceous glands of face. 



Family Acaridce. Mites. Microscopic, soft-skinned. 

 Legs short, with disks for prehension. 



33. Acarus, or Sarcoptes Scabiei. Itch-mite. Body 

 round, arched, with transverse striae covered with spines 

 and bristles. Young have but one pair of feet. 



Family Ixodce. Ticks. Larger, blood-sucking mites, 

 with firm back-shield and dentated mandibles. Live on 

 plants, and occasionally on man. The female inserts its 

 proboscis, and fills itself with blood, causing pain and 

 suppuration. There are several species. 



Family Trombididce. Running mites. Body brightly 

 colored, covered with hair. They live on plants, etc., but 

 sometimes on man. The Leptus autumnalis, gooseberry 

 or harvest mite, is often troublesome in summer. 



Class Hexapoda. Insects. 



Order Rhynchota. 



Sub-order Aptera. Wingless insects, with short, turned- 



