62 Trans. Acad. Sci. of St. Louis. 



eyes, enlarged at the posterior end, where two small simple hairs are 

 situated, and extending forward to the anterior tubercle which bears 

 a whorl of bristles like those of the body. A small single pair of eyes 

 situated two-thirds the distance from the dorsal groove to the lateral 

 margin. 



Abdomen not separated from the cephalothorax. Body two-thirds as 

 broad as long, broadly rounded behind. 



Anterior pair of legs fully as long as the body; tarsus of leg I very 

 slightly swollen, two thirds as long as the tibia; tibia not as long as the 

 antepenultimate segment. Second pair of legs three-fifths as long as 

 the anterior pair; third pair slightly longer than the second pair. Last 

 pair of legs extending one-half their length beyond the posterior margin 

 of the body; tarsus one-half as long as the tibia, not swollen; tibia 

 slightly longer and narrower than the antepenultimate segment. All 

 the legs clothed with hairs similar to those of the body. 



Length, 1.6S mm.; breadth, 1.00 mm. 



In moss. Collected by L. M. Smith at Marion, 111. 

 Trombidiidae. 



Last segment of palpus transformed into a thumb, penultimate ending 

 in one or two strong palpal claws; cephalothorax small and frequently 

 partially concealed by the protruding of the anterior part of the abdo- 

 men; eyes stalked; tarsi frequently swollen. Larvae parasitic upon 

 insects. Adults usually predaceous. 



Trombidium Fabricius. 



Includes forms in which the palpus ends in a single stout claw. 



Two species. 



KEY TO SPECIES. 



Body black, with the legs red T. sudnigrum. 



Body and legs red T. tnissouriense. 



Trombidium subnigrum n. sp. 



PI. IX. f. 15. 



Alcoholic specimens very dark brown; legs lighter. 



Palpi about one-half as long as the anterior pair of legs; palpal claw 

 long, stout and sharp; thumb of palpus not swollen and slightly surpas- 

 sing the claw. With a double pair of eyes, two being situated on a 

 single, short stalk on each side of the cephalothorax just above the 

 anterior pair of legs. Just in front of the eyes is situated a transverse 

 row of four straight, subequal bristles about twice as long as the eye 

 stalks. 



Body broadest at the anterior end and narrowest at the posterior end; 

 subtruncate posteriorly and very sparsely clothed with simple hairs. 



Anterior pair of legs slightly longer than the body; tarsi swollen and 

 thickly clothed with fine hairs, somewhat shorter than the tibia; tibia 

 slightly longer than the antepenultimate segment. Second and third 



