346 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1953 



known." Nymphs of the Protodonata are entirely unknown, but in 

 view of the similarity of the adults to true Odonata, we infer that the 

 immature stages could not have been very different. 



The third type of paleopterous insect in the Carboniferous fauna has 

 no counterpart in an existing order. Although named the Proto- 

 hemiptera, they were closely allied to the Palaeodictyoptera, since they 

 possessed prothoracic wing flaps and other characteristics of the latter. 

 But the mouth parts of the Protohemiptera were modified to form a 

 long suctorial beak, resembling that of certain Diptera, or flies, though 

 differently formed. The Carboniferous members of this order were so 

 much like the Palaeodictyoptera that some of the insects whose head 

 structure is unknown and which have been considered Palaeodicty- 

 optera, were, I believe, Protohemiptera. The members of this order 

 presumably fed either on plant juices from the large club mosses and 

 tree ferns, or on the blood of amphibians and reptiles. 



The neopterous insects of the Carboniferous include a vast and con- 

 fusing assemblage related to the locusts and stone flies. Most of the 

 species belong in the extinct order Protorthoptera, with a few aberrant 

 ones in the Caloneurodea, and still others, obviously true roaches, in 

 the Blattaria. The Protorthoptera show great diversity of structure. 

 The more generalized species had membranous f orewings and cursorial 

 legs; others had leathery wings and either saltatorial or prehensile 

 legs. Essentially, the Protorthoptera possessed the same amount and 

 the kind of diversity that exists among the true Orthoptera, yet it is 

 highly doubtful that any of these Carboniferous forms gave rise 

 directly to the living groups they resemble. 



The roaches were another interesting order in the Carboniferous. 

 Although in numbers of individuals and described species they ex- 

 ceeded all other Carboniferous insect orders, I am convinced that their 

 abundance is very misleading. The swampy areas inhabited by the 

 roaches supplied the best of conditions for their preservation as fos- 

 sils, whereas other insects might encounter such optimum conditions 

 only rarely. This condition would account for a disproportionately 

 large number of roaches preserved as fossils. The extensive series 

 of described species of roaches is due to the fact that Handlirsch and 

 others have ignored the extreme instability of wing venation in both 

 living and extinct types. Apart from their numbers, the most notable 

 feature of the Carboniferous roaches was their close resemblance to 

 species now living. Recently, however, an unexpected structure has 

 been discovered in some Carboniferous roaches from Belgium : a long, 

 projecting ovipositor, fully as long as the abdomen [11]. In all liv- 

 ing roaches the ovipositor is vestigial or rudimentary, and the eggs 



« These particular Insects are the only extinct insects, so far as is known, that were 

 larger than existing species. The inference hos been drawn from the Protodonata that 

 all Paleozoic Insects were very large, but this is not the case. 



