146 Dr. A. S. Packard, Jun., on the Classification of 
orders (the Hemiptera, Coleoptera, Diptera, Lepidoptera, and 
Hymenoptera) have originated. 
We will first briefly summarize the characters, as we under- 
stand them, of the Phyloptera as a whole; then the distin- 
guishing marks of the four orders. 
Superorder PHYLOPTERA®*. 
The mouth-parts are free, adapted invariably for biting, the 
mandibles being toothed and adapted for chewing ; the first 
maxille separate, with three divisions, the outer bearing 
usually five-jointed palpi; the second maxille united to form 
a labium divided into a submentum, mentum, and ligula, the 
latter varying much, being either cleft (Pseudoneuroptera) or 
entire (Neuroptera), and bearing usually a three-jointed palpus. 
This is the primitive elementary condition of the mouth-parts, 
and such as obtains in Coleopterous larve. ‘The head is 
notable from the great development of the epicranium. The 
clypeus is often divided into two portions, a posterior (post- 
clypeus) and anterior (anteclypeus) ; in the other and higher 
orders the clypeus is entire. 
The prothorax is usually very large and square; but in a 
few families, as the Phryganeide, Panorpide, Psocide, Libel- 
lulidee, and Ephemeridee, it is small and collar-lhke. There is 
a marked equality in size and form of the meso- and metatho- 
rax ; in most Orthoptera and some Pseudoneuroptera and Neu- 
roptera the metathorax is often even larger than the meso- 
thorax ; in this respect the Phyloptera differ from any of the 
higher Hexapoda. In both of the two hinder segments of 
the thorax the four tergal sclerites, viz. the preescutum, scutum, 
scutellum, and postscutellum, are each well developed, and 
more equably so than in any other order. The scutum is 
deeply excavated in front to receive the often large subtrian- 
gular or cordate prescutum; and in some genera the scutum 
is, so to speak, cleft in two by the meeting of the prescutum 
and scutellum in the median line. The flanks of the thorax 
or pleurites, are often very large, and the episternum and epi- 
merum are broad, oblong, or squarish ; and these sclerites are 
sometimes subdivided into an upper anda lower division (supra- 
and infra-epimerum or episternum). ‘The sternum is often 
large, flat, and broad ; it 1s sometimes divided into a sternum 
and preesternum. 
The wings are usually net-veined, often with numerous 
longitudinal veins, the branches of the subcostal, median, and 
submedian veins being either very long and parallel with the 
* From dddo», gens, nation; mrepdy, wing. 
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