24 University of Michigan 



long, those proportionately shortest and widest being the four 

 immediately preceding the ultimate (Plate IV, Fig. 22). 



Prelabral region with six setae, a postantennal series of 2+2 

 and two setae following, one behind the other, on the median line. 



Labrum simple, non-chitinous. 



^Mandible with about eleven teeth of which the most ventral 

 are largest. 



Prosternum with chitinous lines present, these light. Anterior 

 margin widely and evenly concave. Prehensors short, joints all 

 unarmed, but claw serrate at base within (Plate V, Fig. 23). 



Dorsal plates conspicuously roughened with transverse ridges 

 or series of short rugae or tubercles which bear setae. Last 

 dorsal plate shield-shaped, broad at base with sides convex and 

 strongly converging to the narrowly rounded caudal end. 



Ventral pores present in a circular area on all sternites from 

 the first to the penult inclusive. Sternites with numerous long 

 setae, these arranged in general in four longitudinal series, with 

 five or six setae in each, and sometimes several irregularly placed 

 setae. Presternites with setae in a transverse series. The pleu- 

 rites also with straight setae. 



Setae of legs similar to those of body, numerous. 



Last ventral plate long, strongly narrowed caudad from 

 middle in front of which the sides are subparallel; caudal margin 

 short and straight (Plate V, Fig. 24). 



Anal legs, in the male at least, strongly thickened, subconi- 

 cally narrowing from base to distal end. Setae straight and stiff, 

 numerous, a longitudinal ventral series of somewhat larger special 

 setae on each leg over its entire length as in /. lilacinus Cook. 

 Coxopleural pores two on each side, these simple, with the posterior 

 one t}'pically considerably larger than the anterior (Plate V, 

 Fig. 24). 



Pairs of legs, forty-nine in one specimen and fifty-five in two. 



Length, 21, mm. 



