510 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
as wide as head; nearly as wide across anterior as across posterior 
border; 2.6 times wider than long. 
Antennae very short, filiform; only about 2.25 times longer than the 
head. Articles short; the ultimate a little shorter than the two 
preceding ones taken together. Hairs very short and rather dense; 
increasing in length on proximal articles. 
Claws of prehensors very slender, narrow at base; unarmed; when 
closed surpassing the anterior margin of head and attaining the distal 
end of the first antennal article. None of the articles armed. 
Margin of prosternum between the prehensors wide; forming a 
gently reéntrant angle. Sides convex; strongly converging caudad. 
Wider than long in ratio 7:4; 1.7 times longer than greatest length of 
the femuroid. Chitinous lines distinct but incomplete at anterior 
end. 
First dorsal plate a little wider than the basal plate; sides convex, 
converging caudad. Plates not sulcate. 
Anterior ventral plates each with caudal border transversely con- 
spicuously depressed or channelled and at middle with an angular 
process fitting into a corresponding process in the anterior border of 
the succeeding sternite. 
Last ventral plate very broad; wider than the preceding one. 
Sides strongly converging caudad; caudal margin wide, weakly 
convex. Wider than long in about ratio 5:3. 
Ventral pores numerous; arranged in a transverse band each side 
of the middle line and immediately in front of the caudal margin, 
the band on each side widest at ectal end. 
Coxopleurae not large. Pores on each appearing as two pits near 
or partly beneath edge of sternite. 
Spiracles all circular and small, scarcely differing in anterior and 
posterior regions; the first one not at all enlarged. 
Anal legs distad of coxopleurae a little shorter than the penult pair. 
In the male strongly crassate; thickest at femur; ultimate article 
short, conically rounded distad. Clawless. Densely finely pubescent. 
Legs of first pair a little shorter and more slender than those suc- 
ceeding. Anterior pairs a little more robust than the posterior ones. 
Pairs of legs 43 (<7). 
Length 24 mm. 
Locatity.— Mexico: Hidalgo; Guerrero Mill (W. M. Mann). 
Type, M. C. Z. 1715; one specimen. 
