PROC. ENT. SOC. WASH., VOL. 23, NO. 2, FEB., 1921 35 



margins, all spines black at the tip and along the lower margins, those of the 

 posterior ones more conspicuously black; anterior and intermediate femora with 

 blunt blackish teeth on the anterior margins only, the posterior femora long 

 and strongly swollen in the basal two-fifths, armed below on both margins with 

 a few short piceous teeth; plan tula of posterior tarsus free but short, about one 

 half as long as the 'basal tarsal segment. Organs of flight fully developed, 

 extending to or beyond the tips of the posterior femora; tegmina broader in the 

 male than in the female, greenish in both sexes and with the main veins in the 

 female blackish basally; tympanum of male abou! as long and broad as the pro- 

 notum; wings clear hyaline with a greenish cast along a narrow costal strip in 

 the apical half of the wing, the longitudinal veins mostly dark colored. 



Length, pronotum, male, 8 mm., female, 9.5 mm.; tegmina, male, 47 mm., 

 female, 42 mm.; posterior femora, male, 34 mm., female, 36 mm.; cerci, male, 

 4.5 mm., female, 2.75 mm.; anal stylets, male, 2.75 mm.; ovipositor, 23 mm. 



Described from one male and one female, type and allotype. 



Type and allotype in Collection of the U. S. National Mu- 

 seum. 



Catalogue No. 22976. 



The collection contained an adult male and a male nymph of 

 another species of this same genus which seems allied to the one 

 described above, except that the cerci and anal stylets are shorter 

 and there are other characters, both structural and colorational, 

 that indicate specific distinctness from mokanshanensis. The 

 absence of all legs, except the right fore leg, from the only adult 

 specimen makes determination difficult, and it is deemed best 

 to leave this form unplaced until more and better preserved 

 material is obtained. 



NOTES ON THE ANCESTRY OF THE HYMENOPTERA. 



BY G. C. CKAMPTON, PH. D., 

 Massachusetts Agricultural College, Amherst, Mass. 



To any one who makes a study of a large number of structures 

 from different parts of the body, in attempting to determine the 

 origin and affinities of the various orders of insects, it very soon 

 becomes apparent that it is utterly impossible to arrange the 

 lines of descent of the insectan orders in a dichotomously 

 branching tree drawn in one plane, since several orders are fre- 

 quently connected by mutual bonds of relationship, and many 

 lines of descent may converge toward a common ancestry, which 

 is anatomically intermediate between two or more primitive 

 groups, and is related to the one scarcely less closely than to the 

 others. If we disregard the factor of time (i. e., whether one 

 order was derived from the common ancestral group sooner, or 

 later, than certain others derived from the same ancestral 

 group) and consider the ancestral group from which the others 

 were derived as merely an anatomical "point of origin," the 



