DESCRIPTION OF THE NEUROPTERA. 
293 
markable, mask like labium. The abdomen is very long, slender and 
cylindrical ; there are eleven uroineres, the eleventh being well repre- 
sented, while the cercopoda are not jointed, but in the form of claspers. 
3. Ephemerina . — In the small epicranium, and the large male eyes, the 
Ephemeriaa resemble the Odonata, though the rudimentary mouth- 
parts are in plan entirely unlike them. So, also, the prothorax is small 
and annular, but the subspherical, concentrated thorax is remarkable for 
the large mesothorax and the small metathorax. Hence the hind wings 
are small and sometimes obsolete. The long, slender abdomen has ten 
uromeres, and bears, besides the two long, filamental multiarticulate 
cercopoda, a third median one. 
The larv® of the lower Odonata and of the Ephemeral® closely ap- 
proach in form those of the Perlid®, showing that the three suborders 
here mentioned probably had a common ancestry, which cau be theo- 
retically traced to a form not remote from Campodea. By reason of the 
general resemblance of the larval forms of these three suborders it would 
be inadvisable to separate the Odonata and Ephemerina from the Pla- 
typtera, although, when we consider the adult forms alone, there would 
appear to be some grounds for such a division. 
Order 4. NEUROPTERA. 
The head is horizontal and somewhat flattened, except in the Tricli- 
optera and Pauorpid®, where it is subspherical and vertical. The body 
shows a tendency to be round or cylindrical, the thorax being' more or 
less spherical, but there is great diversity in form from the Sialid® to 
the Trichoptera. The mouth-parts are free and the mandibles well de- 
veloped, except in the Trichoptera, where the mandibles are nearly 
obsolete iu form, and functiouless, thus suggesting or anticipating the 
Lepidoptera. 
In the Neuroptera the ligula is entirely unlike any of the foregoing 
and tower groups. It is entire, forming a broad, flat, large, rounded 
lobe; it is largest in Myrmeleon, Ascalaphus, and Mantispa, but smaller 
in Oorydalis, where it is also narrower, and indented on the front edge. 
Iu Panorpa the ligula is minute, rudimentary (PI. LIX, tig. 7). In 
the Trichoptera it is also minute and rudimentary (PI. LIX, fig. 5). 
The prothorax is usually (Plauipeuuia) large, broad, and square, but 
is ring- or collar-like iu the Trichoptera, being short and small, much 
as iu Lepidoptera. Except in the Trichoptera, the meso- and metanotum 
are characterized by the large, cordate pr®scutum, and in the Heuiero- 
biua the metascutum is partially or (iu Ascalaphus) wholly cleft, the 
prmscutum and scutellum meeting on the median line ot the thorax. 
In the Hemerobiua and Sialid® the metathorax is as large, or nearly 
as large, as the mesothorax, and the hind wings are as large as the 
anterior pair. The wings are not net- veined, the type of venation being 
entirely unlike that of the Ortlioptera aud Pseudoneuroptera. The 
