1925 ] External Anatomy of Head and Abdomen of the Roach 199 
borne by it, and the maxillae are closely associated with it. Yuasa, 
1920, calls it the “maxillaria.” Holmgren considers that it rep- 
presents the labial segment in embryonic termites. It bears the 
occipital condyles labeled x in Fig. 13, and the cephaligers (z of 
Fig. 13) or head-bearing processes of the lateral cervical sclerites 
articulate with these condyles. Two occipital tendons oct fur- 
nish attachment for muscles, as also do the small cervical tendons 
y. The Cushion-like prominences labelled tpn in Fig. 13 lie 
near the gular pits which are the external manifestations of the 
invaginations forming the posterior arms of the tentorium. 
When the mandibles, maxillae and underlip are removed, and 
the head capsule is boiled in 10% caustic potash to remove the 
muscles and other soft parts (which are removed by washing them 
out with a pipette, of by plucking them away with a fine forceps) 
one may observe the inner beam-like structures called the ten- 
torium. These structures serve as supports for muscle attach- 
ment, for buttressing and strengthening the head capsule, and 
for holding in place the brain and other delicate structures within 
the head. 
As shown in Fig. 13, the tentorium consists of the following 
parts. The posterior arms pot (called the postentoria, or the 
“metatentoria” by Yuasa — though the prefix “met a” should 
be restricted to structures belonging to the metathorax) arise 
as invaginations of the gular pits gp (Fig. 11) situated just be- 
neath the pad-like tentorial prominences labelled tpn in Fig. 13; 
and these invaginations forming the posterior arms of the ten- 
torium unite to form the tentorium proper, or body of the tento- 
rium etn , called the eutentorium, or “corpotentorium.” An 
invagination from each of the frontal pits fp of Fig. 5 forms one 
of the anterior arms of the tentorium labelled ptn in Fig. 13, and 
these anterior arms of the tentorium are called the pretentoria. 
They unite to form a transverse plate labelled itn, which is called 
the intertentorium, laminatentorium, or frontal plate of the 
tentorium (Comstock & Kochi). Backward prolongations of 
the structure itn extend on each side of the neuroforamen nf to 
connect the plate itn with the body of the tentorium etn; and the 
dorsal arms stn or surtentoria (supratentoria) extend upward to 
the region of the antennal sclerite ban of Fig. 5. There are thus 
