THE ACARIXA OR MITES. 95 



Mandibles small or inconspicuous; a line between cephalothorax and abdo- 

 men; claws alike in number on all legs 2 



2. Cephalothorax movably attached to the abdomen; palpi four-jointed ; no 



chitinous sternum, and venter naiTOW Hoplodermatid^ 



Cephalothorax not movable; palpi five-jointed; a cliitinous sternum; 



venter broad -. Oribatid^ 



Family ORIBATID.E. 



In the tme Oribatidse there are a great many genera, and there appears to be much 

 doubt as to the proper names of several of them, owing to the work of old authors who 

 had no idea of the ndes of modern 

 nomenclature. 



Oudemans and several other acarol- 



ogists have aiTanged the oribatid 



mites in seven or more subfamilies, 



bas'ed largely on the presence or 



absence of the "wings" or ptero- 



morphae, the existence of strong 



cephalic lamellae, and the tliick- 



ness of the legs. The development 



of the pteromorphse is very gradual, 



and there are plenty of li\'ing repre- i^ 



sentatives whose pteromorphae are 



so small as to make the character 



, . nrr- I'iG. 187 .—Liocarus nitidus. (Author's illustration.) 



an uncertain one. The same may ^ 



be said of the legs, there being many gradations between the very slender and the 



thick and roughened ones. Differences in these points are, therefore, of J^axdly 



generic value. The better-known genera are in the following table: 



1. Abdomen Avith winglike expansions at the anterior sides 2 



Abdomen ^vithout such expansions 8 



2. Superior bristles spatulate; three claws to each tarsus Pelops. 



Superior bristles not spatulate 3 



3. The wings attached to the cephalothorax as well as to the abdomen, at least 



apparently so 4 



The wings attached apparently only to the abdomen 6 



4. Tarsi I and II broad at tips; three claws to each tarsus 5 



Tarsi I and II tapering to a point; one claw to each tarsus; no suture be- 

 tween cephalothorax and abdomen Tectocepheus. 



5. Tarsus II ver\' short, broad, cup shaped Oripoda. 



Tarsus II slender, not cup shaped Gymnobates. 



6. One claw to each tarsus Orihatodes. 



Three claws to each tarsus 7 



7. Lamelhe very large and prominent, attached to the cephalothorax for only 



a part of their length Orihatella. 



Lamellae smaller, attached to the cephalothorax for their entire length. .Galumna. 



8. Cephalothorax with lamellae 9 



Cephalothorax without lamellae 17 



9. With one claw to each tarsus; tibia pedicellate 10 



With three claws to each tarsus 11 



10. Body smooth above Oribella. 



Body more or less sculptured or roughened above Carabodes. 



11. Legs II, III, and IV arising from well beneath body 14 



Legs II, III, and IV arising from near edge of body 12 



12. Trochanter III vrith a very long, prominent bristle; abdomen smooth. .Notaspis} 

 No long bristle on trochanter III 13 



13. Lamellae submedian; tibiae much longer than the tarsi Eremaeits. 



Lamellae sublateral; tibicC but little longer than the tarsi Oribatula. 



1 Type is N. bipilis Herm., fixed by Nicolet; Hermann gave no type. 

 88854°— 15— 7 



