June, 1918 Bulletin of the Brooklyn Entomological Society 61 
being many-segmented in some insects, while in others they are 
composed of a pair of unsegmented appendages. Heymons and 
his followers do not apply the term cerci to the structures labeled 
“c” in the Odonata shown in Figs. 1, 2, etc., since they do not 
believe that these structures represent the transformed cerci of 
the early stages of Odonatan development. NHandlirsch, on the 
other hand, maintains that these structures are re-formations of 
true cerci. The reasons for accepting the interpretations here 
given (based upon the location, relation to other landmarks, etc.) 
to the various Odonatan structures will be discussed in a subse- 
quent paper) The cerci of certam Odonata, (e.g. Fig. 1. c- 
bear mesal “teeth’’ and similar processes very suggestive of 
the condition occurring in the cerci of Phasmids and Orthop- 
teroid forms, although the Phasmid shown in Fig. 65 is the 
only one here given which would illustrate this condition in 
the walking sticks. The cerci of many damselflies (Figs. 7 and 
8, “c”’) are much reduced, and in some Odonata they bear pro- 
jecting spines (Fig. 7, “c”), while in others they bear ventral 
membranous areas resembling “callosities” (Fig. 11, “c”’). 
The cerci of the Ephemerids (Figs. 15 and g) resemble those 
of the Lepismids (Fig. 94, “c”) as do those of many Plecoptera 
Gvicei4s co) Ihe cercimc oLtne Onhopteron shown in Pige 
63 resemble those of the Blattid shown in Fig. 92; but the cerci 
inc, OF the remale or Grylloblatian(Mie.o2) ©), are more like 
those of certain Plecoptera, although they are not unlike the cerci 
of certain Mantids. The cerci of the Dermaptera are suggestive 
of those of the Phasmids and Odonata, but certain nymphal Der- 
maptera (@. g., “Dyscritina” longisetosa, Diplatys, etc.) have 
many-segmented cerci similar to those of some Plecoptera. Most 
of them, however, have cerci composed of bttt one segment as in 
saltatorial Orthoptera—although in some of the leaping Orthop- 
tera, as that shown in Fig. 48, the cerci “c” are two-segmented, 
and I find traces of a similar condition in certain Tettigide. The 
cerci of certain Phasmids and Dermaptera are asymmetrical, as is 
true of the cerci of male Embiids. The cerci of the latter insects 
are two-segmented, as in the Zoraptera; but the cerci of the 
Zoraptera are more like the two-segmented cerci of certain Isop- 
tera (Fig. 44, “c”) in regard to the relative size of the com- 
ponent segments. 
