102 PROC. EN T T. SOC. WASH., VOL. 22, NO. 5, MAY, 1920 



ulate on the probable significance of these structures in the Zor- 

 aptera. 



The plate labeled "ep" in Figs. 2 and 4 is apparently made 

 up of the supraanal plate and parapodial plates of the Orthop- 

 teroid insects, and doubtless represents the united tenth and 

 eleventh dorsal segments. Near the base of the region above 

 the anal opening, the cerci "cu" (Figs. 2 and 4) are attached. I 

 formerly suggested that the large central axial spine, which looks 

 like a modified second segment of the cerci in some of Silvestri's 

 figures of the Zoraptera, might represent a second segment of the 

 cerci in these insects. An examination of Zorotypits hubbardi, 

 however, has convinced me that the cerci of this insect are com- 

 posed of but one apparent segment, as is the case in certain small 

 Plecoptera. 



Below the region labeled "ep" in Figs. 2 and 4 is the anal open- 

 ing. There frequently protrudes from the anal region of the 

 apterous forms, a papilla-like projection, which appears to be an 

 everted portion of the rectal region. Since this projection is not 

 visible in all of the specimens, I do not know whether it is the 

 result of squeezing the insect when it was captured, or whether it 

 is associated with the act of defecation. 



The terminal segments of the female differ from those of the 

 male principally in the development of a transverse band-like 

 ventral subanal plate "hp" (Fig. 4), which I have been unable 

 to detect in any male specimens. There thus appears to be one 

 more ventral segment in the females (both winged and ap- 

 terous forms) than in the males, although this additional segment 

 is rather difficult to distinguish in the apterous females, due to 

 lack of pigmentation in these forms as compared with the winged 

 females. The opening of the female reproductive organs is con- 

 cealed by the plate labeled "hg" in Fig. 4, which represents the 

 sternum of the eighth abdominal segment, as in other lower in- 

 sects. The terminal structures of the winged females are very 

 like those of the Isoptera, although those of the apterous males 

 have some features suggestive of the Plecoptera, and their gen- 

 italia are quite like those of the Mantids, Grylloblattids, etc. 



The resemblances between the Zoraptera and other insects 

 may be briefly summarized as follows: The head of a winged 

 Zorotypus is essentially Plecopteroid, with some suggestions of a 

 resemblance to the Psocid type. The neck and prothorax are 

 largely Plecopteroid, while the lateral and ventral regions of the 

 mesothorax and metathorax are quite like those of the Isoptera. 

 The mesonotum and metanotum of the winged forms are more 

 like those of the Psocidae and Neuropteroid insects, such as the 

 Hymenoptera, etc., but also suggest affinities with the Plecoptera 



