266 



Hominoxious Arthropods 



hh. Mandibles in the male chelate (fig. 158 j), in the female long, 



styliform. Parasitic on birds Dennanyssus Dug. 



Two species of importance may be noted, D. hirundinus 

 and D. gallinae. The latter (fig. 51) is a serious pest 

 of poultry, sometimes attacking man, causing itching 

 and soreness, 

 ee. Anal plate absent. In lungs and air passages of some mammals. 

 Halarachnin^. 



dd. Free or attached to insects, rarely on vertebrates. 



e. First pair of legs inserted within the same body opening as the oral 

 tube; genital apertures surrounded by the stermmi. On in- 

 sects Uropodid/e. 





Oe^ru'iaJ- y.ieeve. 







154. Rhicephalus sanguineus, male. 

 After Nuttall and Warbur- 

 ton. 



ee. First pair of legs inserted at one side of the mouth opening; male 

 genital aperture usually on the anterior margin of the sternal 



plate Gamasidae. 



This family contains a number of genera, some of which are found 

 upon mammals, though the majority affect only other artho- 

 pods. One species, Laelaps stabularis, frequents the bedding 

 in stables, and in one instance at least, has occasioned irri- 

 tation and itching, in man. 

 bb. No distinct spiracle in the stigmal plate on each side of the body. 



c. Body usually coriaceous, with few hairs, with a specialized seta arising 

 from a pore near each posterior comer of the cephalothorax; no eyes; 

 mouth parts and palpi very small; ventral openings of the abdomen 



large; tarsi without sucker. Not parasitic ORIBATOIDEA. 



cc. Body softer; without such specialized seta. 



d. Aquatic species HYDRACHNOIDEA. 



dd. Not aquatic. 



