1921] Crampton: Sclerites of the Head 83 
The Dermapteron shown in Fig. 7 is a primitive, but highly aberrant 
earwig, and the condition occurring in its mouthparts may therefore 
not be as typical as though another form had been chosen to illustrate 
the group. In all of the Dermaptera which I have examined, however, 
the paraglosse “‘pg”’ (Fig. 7) are long and slender, and the gloss have 
apparently been lost, so that these features, in conjunction with the 
peculiar character of the gula ‘‘gu’”’ (which is a narrow transverse 
sclerite in the earwigs) may be of value in characterizing the order 
Dermaptera. 
In the larvee of the Neuroptera related to the Myrmeleonide (Figs. 
44 and 47) there is a tendency for the gula, ‘“‘gu,’”’ submentum, ‘‘sm,”’ 
and mentum, ‘‘mn,’’ to unite, while the antero-lateral structures 
labeled “pgr”’ bearing the labial palpi, “‘Ip,’’ acquire a greater mobility 
to compensate for the loss of movement on the part of the rest of the 
labial structures. The structure labeled ‘‘pgr’’ in Figs 44 and 47 may 
not be the exact homologues of the palpigers ‘‘pgr’’ of other insects: 
since other portions of the labium probably enter into their composition: 
but the term palpiger as applied to the structure in question is sufficiently 
accurate for practical purposes. In the neuropterous larva shown in 
Fig. 46, the labial palpi are apparently composed of more than the 
usual three segments found in the palpi of most Orthoptera, etc., and it is 
quite probable that a secondary segmentation of the palpi has taken 
place in the Neuropteron in question. Faint indications of such a 
secondary segmentation of the labial palpi, ‘‘lp’’ are to be found in 
the larva shown in Fig. 51, in which the labial palpi are either composed 
of but three actual segments, with a distinct palpiger having the appear- 
ance of a fourth segment, or a fourth segment has been formed in an 
originally three segmented labial palpus. The fact that the palpi 
are but three-segmented in the primitive neuropterous larvae shown in 
Figs. 23, 12, 15, etc., would indicate that three is the original number of 
the labial segments of the group as a whole. In connection with the 
discussion of the labial palpi of the Neuroptera, I would call attention 
to the palpimacule, “‘pm,”’ or sense organs borne on labial palps of the 
Myrmeleonid shown in Fig. 70. A similar sense organ occurs on the 
labial palp of Nymphes (Fig. 72, ‘“pm”’) and this fact adds weight to the 
view that the Myrmeleonidee and Nymphes are quite closely related. 
The maxille of an insect are homologous with the first maxille 
(not the second maxillz, as Folsom and others maintain) of Crustacea, 
as may be seen by comparing an embryo of any primitive insect, with 
the embryo of a crustacean, such as the isopodan Jaera, figured by Mc- 
Murrich. The sternal region of the maxillary segment takes part 
in the formation of the hypopharynx, or tongue-like structure on the 
floor of the pharyngeal cavity, while the pleural region of the maxillary 
_ segment enters into the composition of the posterior region of the head, 
called the “‘trophiger,’’ which is situated near the occipital foramen, or 
posterior opening through which the nerve cord, gullet, etc., pass into 
the head capsule. The pleural region of the maxillary segment is 
demarked from the pleural region of the labial segment behind it by 
