56 PROCEEDINGS OE THE NATIONAL MUSEUM. vol. xxvm. 



three families — the Derinanyssidie, the Ganiasidiv, and the Uropodida\ 

 They are not, however, as distinct as one coukl wish. The\' may best 

 be separat(Ml as foUows: 



1. Parasitic on vc-rtcbrateH; mainlil^UiS fitted fur piercing; body sometimes con- 



strirtci 1 1)er)iianijssl(la 



Free, or attaciied to insects (rarely on vertebrates, never on Ijirds) 2 



2. First pair of legs inserted within tiie same body-opening (camerostome) as the 



oral tnlie; dorsum of body projects beyond the camerostome; genital apertures 



surrounded ])y the sternum UropodUhc 



First iiairof legs inserted at one side of the mouth opening; dorsal surface of 

 bodv does not project in fr(,)nt of the camerostome, male genital aperture usu- 

 al! v on tlie anterior margin of sternal plate (sometimes in the middle). 



(r(iiit<ti<'idir 



The true (Jamasidie are divided into a o-reat number of o-enera. The 

 family has not been earefidly studied in the United States, so that the 

 followinj^' table to the more prominent known genera includes .several 

 not yet recorded from the United States: 



1. biviiig in the ears of cattle, liorses, etc Rallliefia 



Living upon moles, or in their nests HivniogdjiKism 



Not ft lund on vertebrates 2 



2. No peritreme, only the spiracle; leg I without claws; dorsal shield entire 3 



Peritreme present 4 



3. Spiracle elliptical; male genital aperture in anterior margin of sternal plate. 



Ij>}i iopis 

 Spiracle, circular.; male genital aperture in middle of sternum Epirfh(s 



4. Peritreme very short, about twice as long as wide; dorsal shield entire; leg I 



with claws; living in a cavity of the alxlomen of certain bees {Xylocopa). 



• fj'rcfn iclla « 

 Peritreme more than twice as long as broad; not jiarasitic on l)ees 5 



5. Leg I without claws; dorsal shield undivided 6 



Leg 1 with claws 10 



6. A post-anal plate; genital aperture of female Itetween second and third coxa-, 



and opening by two hinged plates; male with ventral plates united, and leg II 



unarmed CeLrnopsis 



No post-anal plate; female genital opening normal, and farther back 7 



7. Hind femora with several distinct teeth beliind; leg II of male unarmed; male 



genital opening in middle of sternum Megist}(anus 



Hind femora unarmed, or, if so, then leg 11 is enlarged and armed in male, and 

 male genital aperture on anterior margin of sternal plate 8 



8. Peritreme not extending in front of cox;e III; body short; legs short; male with 



leg II unarmed; male genital ai)erture opens in middle of sternum; attached 



to arthropods Antennophorns 



Peritreme extending much in front of cox;e III; male genital aperture on anterior 

 margin of sternum 9 



9. Male with leg II enlarged and armed with teeth; female often with metasternalia; 



jieritreme often curved at base; body more elongate Macroche/es 



Male with leg II unarnied; all legs very long; female without metasternalia. 



Fodocbnnn 

 10. MiddU' of dorsum with two small shields each side, a larger one at tip, and a very 



large one in front Liroa^pis 



Dorsum without such arrangement of shields, usually one, oi- one transversely 

 divided 11 



"New name to replace Oreenia Oudemans (1900), preoccupied by Kirby in 1896. 



