Packard.) 194 {June 16, 
to be no reasonable doubt but that it is a modified form of a small hairy 
Lysiopetaloid form, with antennse exactly like those of Trichopetalum, 
Zxeonopus Ryder. 
Zygonopus Ryder, Proc. U. 8. Nat. Mus., iii, 527, Feb. 16, 1881. 
Body rather slenderer than in Scoterpes. The head differs from Sco- 
terpes in being much narrower and higher, the swollen sides or gens 
being much less swollen ; the vertex is swollen ; the front as broad as long 
with the upper edge a little hollowed, but quite distinct from the vertex 
itself. The eyes entirely wanting, as in Scoterpes. The antennex are 
rather thick, and in this respect approach Scoterpes, but the sixth and 
seventh joints are much longer, and rather more setose ; the sixth joint is 
about two-thirds as thick as long, and the last (seventh) joint nearly twice 
as long as thick. The sides of the segments are swollen subdorsally as in 
Scoterpes, and the setiferous tubercles are arranged as in that genus, but 
the setse are shorter; the lower posterior edges of the arthromeres below 
the shoulder or hump is chased obliquely with fine impressed lines, The 
feet are less in number than in Scoterpes. The diagnostic characters of the 
genus lie in the remarkably swollen sixth pair of feet of the male, in which 
the second joint is rather thick, while the third joint is long, and with the 
fourth joint remarkably swollen, with a series of about nine oblique re- 
tractor muscles diverging from the proximal end of the terminal joint, 
which is long and slender and straight, with a well-developed claw. The 
seventh pair of the male are of the normal form. The rudimentary or 
eighth pair are like those of Trichopetalum, the second (terminal) joint 
not ending in a claw, thus differing from those of Scoterpes. The male 
genital armature is entirely unlike that of Scoterpes, though it is rudimen- 
tary and minute ; the outer lamina consists of a basal subtriangular portion, 
ending in a long slender curved spine, beneath which is a stouter spine, 
shorter and less curved ; a minute median setose lamina is present, while 
the inner lamina is a weak, slender setose filamentary outgrowth, 
Mr. Ryder’s generic characters are stated very briefly, as follows: 
«Sixth pair of legs very robust, and with the third joint greatly swollen.”’ 
The generic characters are not contrasted with those of Scoterpes. 
This genus differs from Scoterpes in the remarkably swollen, clasping 
sixth pair of legs, and in the male genital armature, while either sex dif- 
fers from Scoterpes in the much narrower head, and longer sixth and 
seventh antennal joints. 
Zyaonopus waiter Ryder. 
Spirostrephon copet Pack., Amer. Nat., xv, 231, March, 1881. 
Zygonopus white: Ryder, Proc. U.S. Nat. Mus,, iti, p. 527, Feb. 16, 1881. 
Hight 3, 102. Body white, long and slender, number of segments 32. 
Head with scattered, fine sete ; antenna with the second joint not quite 
one-half as long as the third, which about equals the fifth in length, both 
