PROC. ENT. SOC. WASH., VOL. 22, NO. 5, MAY, 1920 93 



Male. Similar to the female except the apical segments of the abdomen; 

 here, what is apparently the ninth dorsal segment is roundly prolonged ap- 

 ically, depressed below the plane of the eighth segment, the tip more heavily 

 chitinized than the membranous basal portion, and the apex notched mesially 

 with three minute tuberculous teeth on each side of the notch and with a 

 small hook in the apex of the notch. This last described character is exceed- 

 ingly minute and very difficult to make out even under fairly high magnifica- 

 tion. The apical ventral segment is mesially cut apically by a V-shaped 

 notch, and several small spines are situated on the lobes formed by this notch. 

 The penis is concealed, very rarely visible as a simple minute chitinous point. 



Seventeen females, (i males. One of these females confined in 

 a vial between June 4 and 12, 1919, deposited a single egg, which 

 is briefly described at the end of this description. 



Apterous Unchitinized Adult (or Nymph of Apterous Chitinized Adult). 



Among the lot of a dozen or so specimens examined there are 

 probably three forms represented. First very surely the nymph 

 of the apterous pigmented adult last described, second possibly 

 the reproductive unpigmented adults corresponding to that noted 

 under Z. hubbardi, and the third the nymph of the last. But no 

 morphological character has been found for separating the ma- 

 terial into such divisions, all specimens being essentially alike 

 except for minor variation. This form is essentially the same as 

 the unchitinized apterous adult of hubbardi as set forth in the 

 original description of that species, and as amended and figured 

 in the present paper, except for the specific characters noted in 

 the discussion of the winged form of the present species. 



The constant feature distinguishing this from the corresponding form of 

 hubbardi is the terminal bristle of the cercus being twice as long as the cercus 

 itself, the more coarsely and densely spinous ventral surface of the post fe- 

 mora and especially the more conspicuously black bristled body. The 

 larger and more elongate third segment of the antennae is also diagnostic 

 but, as in the nymph of the winged form, this character grows less marked 

 in the earlier stages of development, the third segment, especially in small 

 specimens, but often also in larger ones as well, being but little or no larger 

 or longer than the second. Probably the best method for the separation 

 of this form of these two species is to examine the specimens under a glass 

 against a white background, when the black hairs and bristles of snyderi are 

 very decidedly more conspicuous than the lighter ones of hitbbardi. 



Specimens of this complex examined range in total length from about 

 l l /2 to nearly 2'/2 mm. 



Larva. 



This stage is represented by a goodly number of specimens. 

 It is apparently impossible to separate those destined to trans- 

 form to winged specimens from those giving rise to apterous 



