CHAMBERLIN: CHILOPODS FROM MEXICO AND WEST INDIES. 9325 
LESTOPHILUS DIDYMUS, sp. nov. 
Dorsum yellowish, pale ochraceous anteriorly. Head darker, of a 
dilute chestnut cast. Legs yellow, the antennae a little darker. 
Prosternum and prehensors dilute chestnut. Venter yellow. 
Body conspicuously narrowed caudad but as usual only slightly 
narrowed cephalad. 
Head anteriorly subsemicircularly rounded but anterior corners 
somewhat angular. Narrowed from frontal region caudad, caudally 
abruptly rounding in mesocaudad with a very short caudal part having 
sides again subparallel. Caudal margin straight. 1.45-+ times longer 
than wide. Basal plate 2.6— times wider than long; as long mesally 
as at sides; its width anteriorly equalling the width of the narrowed 
caudal division of the cephalic plate. 
Antennae short and proportionately thick; 2.2 times longer than 
the head plate. Ultimate article distally conically rounded, about 
equal in length to the two preceding articles taken together. 
Claws of prehensors when closed extending a little beyond distal 
end of the first antennal article. Claw armed at base with a conical 
subacute black tooth. Femuroid with a paler, distally rounded stout 
process or tooth of usual type and a small, rather vague protuberance 
proximad of this. 
Prosternum with two small, well-chitinized conical teeth close 
together, one at each edge of the narrow, shallow median sinus. 
Prosternum a little widest across anterior end. Exposed portion 
wider than long in ratio 47:43; 1.65 times longer than greatest length 
of femuroid. 
Anterior prescuta very short; the others gradually increasing in 
length toward the caudal end where they are of moderate size. Each 
prescutum with a single transverse row of short straight hairs, each 
scutum having a transverse row of fewer similar hairs across caudal 
border and another one across the anterior border. 
Spiracles all circular. The anterior one much the largest with the sec- 
ond intermediate in size, the others decreasing caudad, mostly small. 
Sternites with the usual median longitudinal sulcus which is deep- 
est at or a little caudad of its middle where crossed by a weaker and 
often indistinct transverse impression. 
Ventral pores few; as usual in a narrow transverse band in front of 
the caudal margin. 
Coxopleurae of last pediferous segment moderate in size. Pores 
small, numerous, not dense; occurring above and below, but above 
confined to proximal end where in part covered as usual. 
Anal legs much longer than the penult; slender; clawless as always. 
Bristles sparse, moderate, chiefly at distal ends of articles. 
