NO. 1382. 



THE ACARINA OR MITES— BANKS. 71 



In the true Oril)atid;e there are a great many genera, and there 

 appears to be much doulit as to the proper names of several of them, 

 owing- to the work of old authors who had no idea of the rules of 

 modern nomenclature. The forms, as far as known, can be g-rouped 

 as follows: 



1. Abdomen with wing-like expansions at the anterior sides 2 



Abdomen without wing-like expansions 6 



2. Superior bristles spatulate; niandililes elongate Pelnp.'i 



Superior bristles not spatulate 8 



3. Tarsi broad at tip, three claws (Unrnwhati'R 



Tarsi tapering to tip ^ 4 



4. With three claws to tarsus 5 



With but one claw to tarsus Orllxdodei' 



5. Cephalothorax with lamellfe large, and attached to cephalothorax for only part 



of their length OribatrJla 



Cephalothorax with smaller lamellfe, attached for nearly their whole length, 



nalimDin 



6. Cephalothorax with lamellfe 7 



Cephalothorax without lamellfe 11 



7. Body smooth ,S 



Body more or less rough 9 



8. Legs II, III, and IV inserted mider body LincaruK 



Legs inserted more on side of l)ody Erem,rui< 



9. Cephalothorax and abdomen plainly separated on dorsum 10 



Ceplialothorax and fibdomen more or less united Scutorertcr 



10. Claws three; femora I and II not pedunculate Xntaf<pi>i 



Claw one; femora I and II pedunculate Canibodes 



11. Legs slender, longer than body 12 



Legs short and thick 18 



12. Claws three (fi/mriodauu'cux 



Claw one Orihata 



18. Abdomen transversely segmented Hiipochthouin^ 



Abdomen not transversely segmented 14 



14. Claw one; dorsum convex Ili'DiK/imia 



Claws three 1 -t 



15. Dorsum very convex, with concentric rings Xeoliodi's 



Dorsum quite flat, without concentric rings 16 



16. Leg II with tectopedia; dorsum coriaceous; body elliptical Ci/ndwromviis 



Leg II without tectopedia; dorsum softer; body more rectangular Xoflims 



Most of our common forms belong- to either Galumna or OrUxitella. 

 They are usually shining- black in color, sometimes with a pale s})ot fit 

 fease of abdomen, and rarely with hairs or bristles above. They have 

 the anterior sides of the dorsal integument extended downward in a 

 wing-like 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 awa}'. 



G. 2}ratensis Banks may be swept from meadows in great numbers, 

 and doubtless injures grass to some extent. 0. aquatica Banks lives 

 on aquatic plants, and can readily walk on the surface of stagnant 

 water, yet there seems to be nothing peculiar in the structure of the 



