SUB-PHYLUM III INSECTA 683 
To this lowly organised class of insects belong the Thysanwra and Collembola 
(Spring-tails). Brongniart describes a species of the first group from the Carbon- 
iferous of Commentry (Dasypeltus Lucasz), which 
resembles the living Lepisma, but has only a single 
terminal filament. In amber and the Oligocene of 2 
Florissant a number of species are found,. some of Fic. 1441. 
which belong to still living, and others to extinct  petrobius seticornis, Koch and 
genera. Examples: Petrobius (Fig. 1441), Lepidion, Berendt. Oligocene; Baltic amber. 
se na PY, */1- 
Forbicina, Machilis, etc. Planocephalus, a headless 
form from the Oligocene of Colorado, is regarded by Scudder as the type of a distinct 
sub-order. 

Order 2. ORTHOPTERA. 
Fore wings coriaceous, hind wings thinner, delicately veined, plicated. The five 
principal veins of the wings, with all their branches, extend to the outer margin of the 
wing. Jaws adapted for biting. Metamorphosis incomplete. 
Palaeozoic representatives of this order frequently combine characters which are at 
present distributed among different families. The neuration of their wings also shows 




Fic. 1442. 
Palaeoblattina Douvillei, 
Brongt. Silurian; Jurques, 
Fia. 1443. 
Calvados. 2/3 (after Brongniart). Aedoeophasma Anglica, Scudder. Coal Measures; England. 1/). 
a less marked differentiation than is the case in more recent Orthoptera ; moreover, 
the fore and hind wings differ less decidedly from each other than in the later forms. 
An isolated wing from the Middle Silurian of Jurques, Calvados (Palaeoblattina 
Douvillei, Brngt., Fig. 1442), is one of the oldest of fossil insect remains, but does not 
admit of closer determination ; Brongniart no longer regards it as a cockroach. The 
Carboniferous of North America and Europe yields numerous genera and species, 
which are more or less closely related to typical 
Orthoptera. Some of these are of gigantic propor- 
tions. The richest localities for remains of this 
order are Commentry, France; Saarbriicken and 
Halle, Germany ; Illinois; Ohio ; and West Virginia. 
Many genera are known only by detached wings. 
PAU Segames Gelanbe. Sp.! Coal Among the largest and best preserved forms are 
Measures ; Saarbriicken, Germany. 14. Protophasma, Stenoneuwra, Aedoeophasma (Fig. 1443), 
and Paolia. Smaller forms include Polioptenus 
(Fig. 1444); Oedischia with saltatorial hind legs; Stethanewra, Calonewra, and 
Ischnoneura. Cockroaches, however, were the prevailing type during the Palaeozoic, 
fully 200 species being known, belonging to the genera Ltoblattina, Gerablattina, 
Anthracoblattina, Progonoblattina (Fig. 1445), Mylacris, ete. Spiloblattina from the 
Trias is placed in the same group as the Palaeozoic forms, under the name of Palaeo- 

Fig. 1444. 
