1921] Crampton: Sclerites of the Head 95 
THE HEAD CAPSULE OF THE NEUROPTERA. 
Since the Neuroptera are an extremely important group from the 
standpoint of the study of the phylogeny of the higher insects, I have 
drawn as many types of neuropterous heads as I have been able to 
examine, in order that anyone wishing to find out what modifications 
of the head capsule are to be found in the group, may be able to determine 
which families give indications of being of value for a phylogenetic 
study. Furthermore, although a study of the head region alone is of 
no great value in determining the interrelationships of the members 
of the order Neuroptera, there are certain features of the head region 
which offer indications of relationship between certain insects, and the 
evidence of the head region should be added to that drawn from the 
study of other parts of the body, in attempting to determine the inter- 
relationships of the families of Neuroptera. 
The character of the mouthparts of the larval Sialis shown in Fig. 
23 would indicate that Szalis is as primitive as any of the Neuroptera, 
and the head capsule in general (Fig. 40) of the larva is as primitive as 
any. The secondary marking off of the areas labeled ‘‘pcl’’ on either 
side of the clypeus of the larve of Raphidia and Corydalis (Figs. 41 and 
42) represents a higher degree of specialization than is exhibited by the 
larva of Sialis (Fig. 40). On the other hand, the nature of the occipital 
region, ‘‘ocp,’’ in the head region of the larvee of Raphida and Corydalis 
(Figs. 41 and 42) in addition to the presence of the peculiar sclerites, 
“‘pel,”’ in these larvee indicates a rather close relationship between the 
two, and the line of development of the Rhaphidide and Corydalide 
apparently quickly merge as we trace them back to that of the Sialis 
type. The head of a Chauliodes larva is so like that of a Corydalis 
larva that there is practically no difference between the two, and there 
can be no doubt that Chauliodes is extremely closely related to Corydalis. 
The head capsule of Chauliodes (Fig. 34) furnishes an excellent starting 
point in taking up the study of the head region of the higher Neuroptera, 
and it 1s approached by Polystochoetes and also by Oliarces, Ithone and 
other Ithontide as closely as any other higher forms. Oliarces’ head is 
remarkably similar to that of Ithone, as may be seen by comparing Fig. 
53 with Fig. 52, and there can be no doubt that these two insects belong 
to the same family (Ithontidz) as is also true of Raphisma, although 
Tillyard in his monograph of the Ithontide does not include these 
insects (Oliarces and Rhapisma) in the family. Furthermore, the 
head capsule of the Ithontidz is remarkably like that of the primitive 
Lepidoptera and Trichoptera described by Crampton, 1920, and I am 
convinced that the Lepidoptera and Trichoptera were descended from 
ancestors very similar to those of the Ithoniide. 
With regard to the relationships of the Nemopteridz, which are of 
great interest from the fact that they approach the Mecoptera and 
Diptera in many respects, it must be admitted that the adult heads 
give but few clews as to their nearest relatives. The head structures 
of the Nemopterid Croce, however, have been figured by Imms, 1911, 
and indicate that the Nemopterid type was probably derived from forms 
