92 
Psyche 
[March 
The Isoptera exhibit strong affinities to the Blattodea; evidence 
linking the two groups to a common ancestor is well marked 
between the Mastotermitidae, an archaic termite family, and the 
Cryptocercidae, a family of generalized cockroaches. This theory of 
common ancestry is supported by several comparative morphologi- 
cal and behavioral studies (Emerson, 1965; McKittrick, 1965; 
Ahmad, 1950; Cleveland, 1934; Hill, 1925). McKittrick (1965) goes 
so far as to incorporate both groups into the Dictyoptera, an order 
which also includes the Mantodea. The gut fauna, female genitalic 
structures, anal expansion of the hind wing, morphology of the 
proventriculus, and deposition of eggs in ootheca-like masses are 
much alike in Mastotermes and Cryptocercus. Furthermore, both 
groups inhabit similar habitats. As a consequence, termites have 
often been referred to as merely social cockroaches. This degree of 
relatedness becomes immediately interesting in view of the extensive 
geological record of the cockroaches. 
Fossil cockroaches are first found in deposits from the Upper 
Carboniferous, which makes them among the oldest insects known. 
Furthermore, they comprise 80 percent of the fossil insect fauna 
during that period (Carpenter, 1930) — an indication that they have 
not only existed, but have flourished, for three hundred million 
years. If the similarities between termites and cockroaches are 
indeed the result of monophyletic, rather than convergent or 
parallel evolution, one might speculate on a much earlier origin for 
the Isoptera than is shown by the fossil record. 
McKittrick (1965) admits that the flagellate gut fauna essential 
for cellulose digestion in both groups may have arisen independ- 
ently in each; however, she believes that the similarities in two 
important morphological characters, the female genitalia and the 
dental belt of the proventriculus, represent primitive characters and 
are therefore indicative of a common origin for Mastotermes and 
Cryptocercus. On the other hand, Tillyard (1926, 1936), Cleveland 
(1934), Imms (1919), Carpenter (personal communication), among 
others, believe that the termites were derived from more ancient 
stock and may have evolved during the Late Paleozoic. Hamilton 
(1978) supports the view that social termites arose from “roach-like 
ancestors” in the habitat of dead phloem, and suggests that the 
invasion of Cryptocercus into the same type of habitat was inde- 
pendent of the ancestral termite. The possibility of termite “evolu- 
