66 
Psyche 
[June 
appearing before the preceding pair has completely freed 
themselves from their embryonic membranes. The embry- 
onic membranes slip back toward the nymphs’ caudal seg- 
ments while they are still held by the genital segments 
of the female. When the nymphs drop from the mother 
and move off, the membranes are left behind attached to 
the vestigial ootheca in the posterior part of the female’s 
genital cavity. The ootheca and embryonic membranes 
adhere to the female until all the eggs hatch, after which 
the female expels them, if necessary, with the aid of her 
hind legs. Thus, the birth product of Diploptera is an em- 
bryo devoid of a chorion, ootheca, and even the embryonic 
membrane. This type of birth is characteristic of truly 
viviparous insects (Hagan, 1951). In Nauphoeta and a 
number of other so-called ovoviviparous species the final 
birth product is frequently, if not always, the ootheca 
containing fully matured embryos which begin to hatch 
after the ootheca has passed beyond the caudal extremity 
of the female (Roth and Willis, 1954). We have found 
the pleuropodia of the embryos left behind with the ootheca 
and embryonic membranes; apparently the pleuropodia 
are severed from the body at or before hatching time. 
We (1954) have questioned whether the so-called ovo- 
viviparous cockroaches are truly viviparous because their 
oothecae are first extruded externally during formation 
and then retracted into the brood sac. Hagan (1954) sug- 
gests that the extrusion and retraction of the ootheca into 
a brood sac represents "... a special case of maternal 
care of the ootheca and its ova.” Some oviparous Homop- 
tera place their eggs in a fold in the hypodermis, a loca- 
tion foreign to the reproductive system, until they hatch 
(Hagan, 1953). The extrusion and retraction of the eggs 
of the so-called ovoviviparous cockroaches is comparable 
to the homopteran behavior, with the exception that the 
oviposition site is a brood sac within the reproductive 
system. 
When the new-born nymphs of Diploptera eliminate the 
air which distends their bodies (fig. 18), they may eat 
the embryonic membranes and sometimes the ootheca as 
well. These first instar nymphs are unduly large in com- 
