96 KEPOKT 108^ U. S. DEPARTMENT OF AGEICULTUEE. 



14. Mandibles long and slender, serrate at tips, extensile; ventral apertures 



far apart Serrarius. 



Mandibles normal, chelate 15 



15. Cephalothorax and abdomen joined by a median piece; tibiae I and II not 



pedicellate; lamellae projecting in front of head Scutovertex. 



Cephalothorax and abdomen separated by a continuous line; all tibiae 



pedicellate 16 



16. Abdomen smooth .* Liacarus. 



Abdomen more or less sculptured Banksia.. 



17. One claw to each tarsus 18 



Two claws to each tarsus Eulokmannia. 



Three claws to each tarsus 24 



18. Tectopedia present, legs very long 19 



Tectopedia absent, legs short 21 



19. Cephalothorax and abdomen not separated in the middle; the ventral 



apertures far apart Amerus. 



Cephalothorax and abdomen separated by a continuous line 20 



20. Ventral apertiu'es far apart (more than their diameter) Oppia.^ 



Ventral apertures approximated Orihata. 



21. Abdomen with the anterior lateral parts separated by sulci from rest of 



the dorsum Trizetes. 



Abdomen with transverse sulci Hypochthonius. 



Abdomen entire, no sulci 22 



22. Ventral apertures contiguous Lohmannia. 



Ventral apertures separated 23 



23. Body more or less sculptured; some joints of legs pedicellate Hermannia. 



Body not sculptiu'ed; no joints pedicellate Malaconothrus. 



24. Legs very slender, much longer than body; ventral apertures approxi- 



mate Damaeus. 



Legs shorter or barely longer than body 25 



25. With tectopedia 26 



Without tectopedia 27 



26. Abdomen deeply sculptured above Cepheus. 



Abdomen not sculptured, concave Plateremaeus. 



27. Cephalothorax and abdomen united above, no suture Ameronothrus. 



Cephalothorax and abdomen well separated above 28 



28. Abdomen hard, ^vith concentric lings Neoliodes. 



No such concentric rings 29 



29. Abdomen soft, convex, with more or less distinct transverse lines; ventral 



area very narrow Tripochthonius. 



Abdomen more coriaceous, flat; no transverse lines; A^enter broad Nothrus. 



Most of the common fonns belong to either Galumna (figs. 180, 181) or Oribatella 

 (fig. 186). They are usually shining black in color, sometimes with a pale spot at 

 base of abdomen, and rarely with hairs or bristles above. They have the anterior 

 sides of the dorsal integument extended downward in a winglike expansion. The 

 shape of this "wing" is characteristic in each species. Many species can be sifted 

 from moss. They at first remain quiescent but after a few moments start to crawl 

 away. 



G. huhhardi (fig. 182) occurs in Florida; G. pratensis Banks may be swept from 

 meadows in great numbers and doubtless injures grass to some extent. 0. aqiiatica 

 Banks lives on aquatic plants and can easily walk on the surface of stagnant water, 

 yet there seems to be nothing peculiar in the structure of the tarsi. G. arborea Banks 

 and G. affinis Banks occur on the bark of trees. G. hirsuta Banks is a pale yellowish 

 form, with a bristly body, occurring in dry sandy places. 0. angusta Banks has 

 been taken from the nest of a Texas ant. In 0. arinata Banks (fig. 185) the \\-ing la 

 provided with a long spinelike process. G. emargmata Banks has the \vings emargi- 

 nate beneath and radiately marked; it is widely distributed in the Eastern States, 

 and very common under rubbish and in moss. 



G. persimilis Banks (fig. 183) occurs in the White Mountains and 0. valida Banks 

 (fig. 184) in Virginia. Some species cluster for hibernation and may be found in 



1 Type is 0. nitcns Koch, thus replacing Damacosoma. 



