MITES OF SUBFAMILY HAEMOGAMASINAE — KEEGAN 207 



5. Sternal shield. — Usually distinctively sculptured; with at least 

 three pairs of usual sternal setae in all genera ; species of Haemogam- 

 asus and Isehyropoda possess accessory sternal setae., which are nearly 

 always smaller than the usual setae, and vary in size, number, and 

 position on shield ; both usual and accessory setae may be barbed ; two 

 pairs of sternal iiores in all species ; a third pair may border the pos- 

 terior margin of the shield in some instances; size and position of 

 pores vary specifically ; shape of shield varies considerably ; its poster- 

 ior margin in particular may be nearly straight or invaginated in 

 varying degrees. 



6. Genitoventral sA^e?f/.— Usually bulb-shaped, with a rounded 

 posterior margin, but varies in size and shape, and in a few species 

 possesses nearly parallel lateral margins ; with a pair of usual genito- 

 ventral setae and varying numbers of accessory setae, which are often 

 distinctly smaller and vary in size and position on the shield; both 

 usual and accessory setae may be smooth or barbed ; sculpturing not 

 as distinct as on sternal shield. 



7. Anal shield.— Roughly triangular in outline, with a rounded an- 

 terior margin, but subject to specific variation; its lateral margins 

 may be parallel ; three usual anal setae always present and always the 

 most posterior setae on shields ; accessory anal setae vary in number 

 specifically and individually; they also vary in size and position on 

 shield ; anal setae may be smooth or barbed. 



8. Endopodal shields. — Slender; show little variation. 



9. Metapodal shields. — Small ; show little variation. 



10. Ventral body setae. — Present over ventral surface of body ex- 

 clusive of shields and coxae; vary in size and number and may be 

 smooth or barbed ; usually longest at posterior body margin ; there is 

 a pair of 7netasternul setae about equal in size with posterior usual 

 sternal setae. 



11. Peritreme. — Shape of peritremal shield, particularly its poster- 

 ior end, which encloses the spiracle or stigma, varies specifically ; loca- 

 tion of pores, posterior to stigma, also varies specifically. 



12. Epistome. — Anterior margin of epistome fimbriated; varies 

 in outline specifically ; ftmbriae may be simple or branched and vary 

 in number. 



13. Chelicerae.— Chelae may possess or lack teeth, and they vary 

 specifically ; fixed chela may possess a distal and a proximal seta, as 

 well as a proximal brush or fringe of small setae ; the distal seta, when 

 stout, is termed an in-flated seta; when small and slender it is termed 

 a pilus dentilis ; the pili are usually present on species whose chelae 

 lack teeth. 



14. Maxillary comicidi. — ^Vary specifically in outline ; that feature 

 and the position and relative size of the four pairs of maxillary setae 



