524 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Antennae short and thick, near 2.5 times longer than the head. 
Ultimate article distally obliquely truncate; shorter than the two 
preceding articles taken together. 
Claws of prehensors when closed extending much beyond anterior 
margin of head, attaining distal end of second antennal article. Claw 
at base with a stout conical black tooth just distad of which is a pale 
protuberance. Femuroid at distal end with a much thicker, paler, 
distally rounded process or tooth extending in a distomesal direction; 
near middle of length showing also a slight rounded protuberance. 
Prosternum with anterior margin bearing two acute teeth close 
together, the sinus between them being narrow and not deep, its 
bottom straight. Sides subparallel from anterior end to rounded 
caudal corners. Wider than long in about ratio 7:6; 1.54 times longer 
than ectal height of femuroid. 
Dorsal plates deeply bisulcate; a pair of weaker intermediate sulci 
more or less developed on some of the plates or in place of these a 
single median sulcus on most anterior plates. A transverse sulcus, 
angulate at middle, evident on some of anterior plates. 
Anterior prescuta very short; the others increasing in length caudad 
and becoming long in the middle and posterior regions. 
Spiracles all circular; the anterior one much larger than the third 
with the second intermediate; others of moderate size and not much 
varying from anterior to posterior regions. 
Ventral plates with a distinctly impressed median longitudinal 
furrow which is deepest at middle of length, in some plates with a 
vague transverse furrow crossing this at middle. 
Ventral pores free; present on anterior plates in a narrow transverse 
band across caudal border. Last ventral plate with sides conspicu- 
ously converging caudad; straight or a little incurved. Width across 
anterior end to width across caudal as 9:5; length to greatest width 
as 10:9, twice the width at caudal end. 
For dorsal plate see Plate 5, fig. 6. 
Coxopleurae of anal legs moderately enlarged. Pores small and 
numerous both below and above but not present on most caudal 
portion ventrally and on a still larger caudal area dorsally. 
Anal legs much longer than the penult. Slender; the last article 
slender and moderately narrowing distad. Hairs moderately long, 
sparse. Clawless. 
Pairs of legs in most cases 45; rarely 43 or 47. 
Length 23 to 35 mm. 
Locauity.— Mexico: Hidalgo, Guerrero Mills (W. M. Mann). 
Type, M. C. Z. 1730; many specimens, Type and Paratypes, M. C. Z. 
1750. 
