
16 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
epicranial suture and the mouth. It has the appearance of 
an appendage but is really a portion of one of the head 
segments. 
The Epicranium (épicráne, Straus-Durckheim). — Under this 
term are included all of the paired sclerites of the skull, and 
sometimes also the front. The paired sclerites constitute the 
sides of the head and that portion of the dorsal surface that is 
behind the arms of the epicranial suture. The sclerites con- 
stituting this region are so closely united that they were 
regarded as a single piece by Straus-Durckheim, who also : 
included the front in this region, the epicranial suture being 
obsolete in the May beetle, which he used as a type. 
The Vertex (vertex, Kirby). — The dorsal portion of the epi- 
cranium ; or, more specifically, that portion which is next the 
front and between the compound eyes (Fig. 1, V, V). In many 
insects the vertex bears the paired ocelli. It is not a definite 
sclerite; but the term vertex is a very useful one and will 
doubtless be retained. 
The Qeciput (occiput, Kirby). — The hind part of the dor- 
sal surface of the head. When a distinct sclerite, it is 
formed from the tergal portion of the united postgenae 
described below (Fig. 3, O, O). 
The Gene (gene, Kirby). — The lateral 
portions of the epicranium. Each gena, | 
in the sense in which the word was used 
by the older writers, includes a portion of 
several sclerites. Like vertex, however, 
the term is a useful one. 
The Postgene. — In many insects each 
gena is divided by a well-marked suture. 
This led Comstock! to restrict the term 
gena to the part in front of the suture 
: (Fig. 4, G), and to propose the term 
postgene for the part behind the suture (Fig. 4, Pg). 
The Gula ( gula, Kirby ; piece basilaire, Straus-Durckheim), — 
A sclerite forming the ventral wall of the hind part of the head 
dn certain orders of insects, and bearing the labium or second 
` ¥Comstock and Kellogg. d MK 1895. 


— ud aai aah of 
Fic. 4. 
a cockroach, 


