
686 THE AMERICAN NATURALIST.  [Vor. XXXVI. 
the Diptera, and if this tracing can be effected for the other 
orders of holometabolous insects, it will put the homology- 
determinations on a much better foundation than they now 
have. It is the beginnings of such an attempt that is outlined 
in this paper. 
NEUROPTERA. 
The Neuroptera belong to the holometabolous insects, 7.e., 
insects with complete metamorphosis, but this metamorphosis 
in many forms is of a very simple and straightforward kind as 
compared with the radical metamorphosis of a fly or butterfly, 
for example. The mouth parts of the 
adult insect are, too, of the orthop- 
terous or biting type, and there is 
no question regarding the interpreta- 
tion of the mouth-part homologies. 
Mandibles, maxilla, and labium of 
the neuropterous mouth are obviously 
homologous with the similarly named 
parts of the orthopterous mouth. 
Furthermore, the differences between 
the larval and adult mouth parts are 
comparatively slight, and no question 
i Ge e e ii made regarding. the homologies 
removed. /5., labrum; med. dures between the two sets. Yet it 1s 
per ats së ron pip rA, worth while to trace the development 
labium; Z4. labial palpus; a»^, of the imaginal parts in its more con- 
tntenha. 
spicuous features, and get a first sight 
at the relation between larval and imaginal mouth parts in a 
holometabolous insect. This relation is readily made out in 
the large and familiar neuropteron called the ‘dobson fly,” 
or “ hellgrammite,” Corydalis cornuta. 
Corydalis cornuta (Figs. 1-5).—The mouth parts of the 
larval Corydalis are shown in Fig. 1i, and their orthopterous 
character, together with the details of the various parts, are SO 
. readily apparent that little description is needed. The man- 
. dibles (md.) are very heavy and long ; the maxillae (szx.) have 
a short proximal segment, cardo (not visible in the drawing), 


