Ewing — New North American Acarina. 63 



pair of legs subequal; last pair of legs extending about one-half their 

 length beyond the posterior end of the abdomen. Clavv's of anterior 

 pair of legs reduced in size; clav/s of other legs moderate. 

 Length, 1.00 mm.; breadth, 0.80 mm. 



From trash. Collected by C. R. Crosby at Columbia, Mo. 



Trombidium missouriense n. sp. 



PL IX. f. 16. 



Alcoholic specimens brown. Body somewhat furrowed dorsally. 



Mouth parts large. Palpi two-thirds as long as the anterior pair of 

 legs, with sharp stout claws; thumb of palpus clavate and surpassing the 

 palpal claw. Palpi well clothed with hairs. 



Abdomen subpyriform; broadest near the anterior end; broadly 

 rounded behind and subtruncate in front; clothed thickly with barbed 

 hairs. 



Anterior pair of legs about as long as the body; tarsus of leg I sub- 

 equal to the tibia in length but slightly swollen and more thickly 

 clothed with finer hairs; tibia and antepenultimate segment subequal. 

 Second and third pair of legs smaller than the others. Last pair of 

 legs extending about one-third their length beyond the posterior end 

 of the abdomen; tarsus of leg IV slightly longer than the tibia. All 

 the legs provided with long, stout claws; ambulacra with a series of 

 equal hairs resembling a comb. 



Length, 1.00 mm.; breadth, 0.70 mm. 



In trash. Collected by C. R. Crosby at Columbia, Mo. 



Two specimens. 



Gamasidae. 



Body wath coriaceous shields; mandibles large, chelate; eyes w'anting; 

 first pair of legs not inserted in the same opening as the mouth parts; 

 males often with the second pair of legs either enlarged or armed with 

 spines or chitinous tubercles. Rarely parasitic. Nymphs frequently 

 much resembling the adults. 



Although this family is one of the richest in numbers, 

 but very few species have been recorded from America. 



Macrocheles Latreille. 



Peritreme present; leg I without claws; dorsal shield undivided; with- 

 out post anal plate; hind femora unarmed; male genital aperture on 

 anterior margin of sternum; male with second pair of legs slightly 

 enlarged and usually provided with teeth. 



Two species. 



KEY TO SPECIES. 



Posterior pair of legs extending two-thirds their length beyond the pos- 

 terior margin of abdomen M. clavisetosa. 



Posterior pair of legs extending less than one-half their length beyond 

 the posterior margin of the abdomen M. muscorum. 



