1921] Crampton: Sclerites of the Head 73 
formed regions of no particular phylogenetic significance, since they are 
not demarked in all of the primitive insects. 
The anterior portions of the laterocephalic regions, namely, the areas 
below and behind the compound eyes, forming the ‘“‘cheek’’ regions of 
the head, are called the gene. An approximately vertical ridge or 
suture frequently demarks a posterior region of the gene called the 
postgena by Comstock and Kochi, 1902. When these postgenz extend 
along the gular region of the head, they correspond in a way, to the 
paragular region and hypostoma, described under the discussion of 
the ventral surface of the head capsule. 
At the base of the mandibles (below, or anterior to the genz) is a 
small sclerite called the basimandibula (‘‘bmd”’ of Fig. 39) in the article 
referred to above (Crampton, 1917). This sclerite probably owes its 
origin to the chitinization of a portion of the membrane between the 
mandible and the head capsule. Comstock and Kochi, 1902, call the 
sclerites ‘‘bmd”’ (Fig. 39) the ‘‘trochantin of the mandible,’’ thinking 
that it represents the trochantin or small sclerite at the base of the 
thoracic legs. This homology, however, is entirely fanciful, and it is 
misleading to designate the sclerite in question as the “trochantin”’ of 
the mandible. 
Comstock and Kochi, 1902, describe an occular sclerite surrounding 
the compound eyes; but I am inclined to consider that this area is not 
marked off by a true suture, and I am very sure that it does not represent 
the basal segment of an occular appendage as Comstock and Kochi, 
1902, are inclined to believe. There is, however, in certain lower 
insects, a fairly well demarked sclerite at the base of the antenna, called 
the antennale in a previous paper (Crampton, 1917); and a process or 
projection of this region called the antennifer in the paper in question 
(i. e., the structure labeled ‘‘anf’’ in Fig. 39), frequently supports the 
antenna in the more primitive insects. At the base of the antenna of 
many larval insects (particularly those of Coleoptera and Neuroptera) 
a ring-like area called the basantenna (‘“‘bat’’ of Figs. 41, 42, etc.) occurs 
at the base of the antenna. This area may originate as a projection of 
the head capsule, or through the chitinization of a portion of the membrane 
at the base of the antenna, and I am inclined to account for its origin 
in either of these ways, although this sclerite is regarded as a modified 
basal segment of the antenna by some entomologists. 
Areas called the postcranial regions, or the postcranials (Crampton, 
1920) occur in the posterior portion of the head of certain Trichoptera, 
etc. Traces of these regions are also found in the lower Lepidoptera, 
such as the Micropterygids, etc., but I have not traced them through a 
series of the more primitive representatives of the higher insects, 
though they will doubtless be found in other orders as well. 
The occiput labeled ‘‘ocp”’ in all Figures is the dorsal and lateral 
region about the occipital foramen, or posterior opening of the head 
capsule through which the gullet, nerve cord, etc., pass into the head 
region. A posterior extension of the midcranial suture ‘‘cs’’ divides 
the occiput into two parts in the larva of the Neuropteron Corydalis 
(Fig. 42), and in the beetle larva shown in Fig. 38, the occiput consists 
