Ewing — Neiv North American Acarina. 67 



Gamasus Latreille. 



Peritreme present, more than twice as long as broad; leg I with 

 claws; dorsal shield large, entire; male with genital opening on the 

 anterior margin of sternal plate; leg II of male frequently enlarged and 

 armed with large chitinous horns or tubercles; sternal plate of female 

 scarcely reaching the hind coxae; genital plate of female triangular, 

 being angulate anteriorly. 



Three species. 



KEY TO SPECIES. 



1. Second pair of legs of male not swollen^ 2. 

 Second pair of legs of male enormously swollen G. magmcornutus. 



2. Second pair of legs of male provided with a sharp tooth on the inner 



side of each femur G. oblongus. 



Second pair of legs of male possessing a large horn G. unicornutus. 



Gamasus oblongus n. Sp. 



PL X. f. 25. 



Pale brownish grey; body darker than the appendages. 



Palpi three-fifths as long as the anterior pair of legs; distal segment 

 equal in length to the penultimate but not so stout; penultimate segment 

 with a sharp spine at its inner distal aspect; antepenultimate segment 

 both longer and stouter than the penultimate segment and bearing two 

 small spines on its inner side; second segment, the stoutest of all and 

 with one small spine on its inner side; mandibles stouter than the palpi 

 and when extended may surpass the same, chelte as long as the two 

 distal segments of the palpus and uniformly toothed on their inner 

 margins. The mandibles are jointed toward their middle. Cusps of 

 the hypostoma sharp, slightly curved and about one-half as long as the 

 chelae of the mandibles. 



Body broadly rounded behind and subtruncate in front, slightly com- 

 pressed just above the second pair of legs. Dorsal surface of the body 

 sparsely clothed with clavate bristles, including a prominent straight 

 shoulder pair and a curved pair situated on the posterior margin. 



Anterior pair of legs slightly longer than the body; tarsus one and 

 a half times as long as the tibia; tibia and antepenultimate segment 

 subequal. Claws of the anterior pair of legs smaller than the others and 

 situated on very slender pedicels. Second pair of legs stouter than the 

 rest; hind pair of legs as long as the anterior pair and with long slender 

 tarsi. All the legs are provided with rather stout bristles. 

 Length, 0.50 mm.; breadth, 0.30 mm. 



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



Gamasus unicornutus n. Sp. 



PI. X. f. 26-27. 



Light yellowish brown; chelae of the mandibles darker brown than the 



rest of the body. 



