500 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
anterior border meeting a semicircular transverse sulcus the convexity 
of which is caudad. Sulci on the remaining plates parallel or very 
nearly so. On the third plate an oblique sulcus runs from the anterior 
end of each longitudinal sulcus obliquely ectocaudad. Some tergites 
of the posterior median region may show two longitudinal sulci close 
together and embracing between them a slight median ridge, but no 
true keel is present on any of the plates. The last dorsal plate with 
the caudal margin arcuate, the median portion protruding convexly 
with each lateral end becoming transverse or nearly so. 
Ventral plates smooth and unfurrowed excepting for a transverse 
subsemicircular impression or furrow toward anterior end of each 
plate, this furrow usually more distinct in caudal region. Last 
ventral plate nearly equal in length and breadth. Sides convex, 
strongly converging caudad. Caudal margin mesally angularly 
emarginate. 
Coxopleural processes moderately long, straight; the distal spine 
slender and acute. Process armed on ventral surface mostly with two 
spinules, but sometimes with only one. Caudal border of coxopleura 
also bearing usually two spinules. 
Spiracles typically circular; the first very much larger than the 
succeeding ones, sometimes appearing more or less elongate. 
Tarsi of all legs biarticulate. Second tarsal joint of anterior legs 
bearing a slender ventral spine near middle. Tibia with a small 
ventral but no lateral spine at distal end. Femora of all legs with 
ventral spinule at distal end. Prefemora with mostly two or three 
ventral spinules. 
Penult legs with femur and prefemur bearing a considerable number 
of spinules chiefly on dorsal and mesal (caudal) surfaces. 
Prefemur of anal legs bearing on ventral surface a longitudinal 
series of four long spines of which the most distal is farther ectad than 
the others and is at the very distal end of the article; these spines 
distinctly shorter than the diameter of the article. Femur with a 
similar ventral series of three spines nearly of same size as those of the 
prefemur; of these the most proximal is farther ectad than the others 
and the most distal one is about one fourth the length of the article 
from its distal end. Femur and prefemur in addition bearing numer- 
ous spinules on ectal and dorsal surfaces. Other joints unarmed. 
Tibia longer than the femur and longer than the first tarsal joint in 
about ratio 13:10. First tarsal joint much more slender than the 
tibia; somewhat angularly extended ventrad at distal end. Suc- 
ceeding portion of tarsus abruptly very much more slender, propor- 
tionately short, commonly not much differing in length from the 
femur; composed of from five to eight distinct articles. Bristles 
sparse, moderate in length. 
Length up to 22-23 mm. 
