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. Claws of anterior 
pair of legs reduced in size; claws 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. 
PA Ast. 20. 
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. resid at Columbia, Mo. 
Two specimens. 
GAMASIDAE. 
Body with coriaceous shields; mandibles large, chelate; eyes wanting; 
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. 
yo 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. 
