170 Annals Entomological Society of America  [Vol. V, 
Family XyYSTODESMIDZ. 
Genus Xystocheir Cook. 
Xystocheir taibona sp. nov. 
Tegument thin, translucent, horn-brown in color, the carinal 
margins pale brick-red; prozonites paler; pigment about dorsal vessel 
commonly showing through as a dark median line. Head very light 
or whitish shining brown, a triangular dark spot below each antenna 
formed of closely arranged small dots. Antenne light yellow or whitish. 
Legs pale yellow or yellowish brown, darker proximally. Venter and 
sides pale brown to yellowish. 
A sharply impressed median sulcus crossing vertex and ending 
abruptly at about level of upper margins of antennal sockets or but 
little lower, crossing near its distal end a shallow furrow which arches 
across from the dorsal edge of.one antennal socket to the other. Vertex 
smooth and shining. <A few scattered bristles over frontal and clypeal 
region. 
Antennze rather long, uniform; clothed with rather short hairs 
intermixed with long bristles, especially on proximal segments. 
First dorsal plate a little wider than the head, shorter than the 
second. Cephalic and lateral margins together semi-circular. 
Caudal margin mesally straight or very slightly incurved, laterally 
extending obliquely cephalad. Entire border margined. ‘Two pairs 
of impressed lines, the two on each side diverging from near the mesal 
line caudo-laterad, the anterior one nearly straight, the posterior curved, 
its convexity caudo-mesad. 
Second plate and those immediately following with lateral portions 
bent cephalad, farther back the plates becoming first straight and then 
with the lateral portions bent more and more caudad. In the anterior 
plates the cephalo-lateral portion bulges cephalad, but in proceeding 
caudad the anterior margin first becomes straight and then the antero- 
lateral corners more and more strongly rounded caudad, the posterior 
corners becoming at the same time more and more strongly produced. 
All scuta distinctly margined. Each segment crossed by two transverse 
sulci of which the more caudal is deepest and longer. 
Nineteenth segment very short, the lateral processes ordinarily 
exceeded by those of the eighteenth segment. 
Anal scutum with process a little depressed, truncate distally where 
it bears several groups long bristles, crossed with two rugose lines a 
double one at posterior third and the other midway between this and 
the apex of process, each line bearing two pairs of double seta, two 
being inserted together in each case. In addition there is a marginal 
couple on each side of scutum farther cephalad. 
Anal valves roughened; inner margins strongly elevated; each valve 
with two sulci extending from anterior margin caudad and somewhat 
laterad, the more mesal one with a double bristle inserted near its 
middle and each valve also bearing at its caudo-mesal angle a compact 
bunch of similar long sete. 
