COCKROACH. 
EXTERNAL CHARACTERS 
REGIon. 
APPENDAGES, 
OTHER STRUCTURES. 
The head is ver- 
tically elongated 
and separated 
from the thorax 
by a neck. 
The insect’s 
head seems to 
consist of seven 
fused segments— 
ocular,antennary, 
intercalary, man- 
dibular, maxillu- 
lar, maxillary, and 
labial. 
The thorax con- 
sists of three seg- 
ments— 
% prothorax, 
4) mesothorax, 
Q metathorax. 
Each segment 
is bounded by a 
dorsal tergum 
and ventral ster- 
num.) 
The abdomen 
consists of 10 
(or x1) distinct 
segments, with 
terga and sterna 
as in the thorax. 
The first sternum 
is rudimentary in 
both sexes, and 
in the female the 
eighth and ninth 
segments are con- 
cealed by the 
large seventh. 
1. The antenna (probably homologous with 
appendages), long, slender, many-jointed, 
tactile. 
2. A pair of stout toothed mandibles work- 
ing sideways. 
3. The first maxille, each consisting— 
(a) of a basal piece or protopodite with two 
joints : a basal cardo, a distal stipes ; 
(2) of a double endopodite borne by the 
basal piece, and consisting of an inner 
lacinia and a softer outer galea ; 
(c) of an exopodite or maxillary palp also 
borne by the basal piece, and consist- 
ing of five joints. 
4. The second pair of maxilla, fused to- 
gether as the ‘‘labium,” consisting—(a@) of a 
fused basal piece or protopodite with two 
joints: a basal sub-mentum, a smaller distal 
mentum; on each side this protopodite 
ears— 
(4) a double endopodite (ligula) consisting 
of an inner lacinia and an outer 
paraglossa ; 
(c) an exopodite or labial palp, consisting 
of three joints. 
(a) First pair of legs. 
(4) Second pair of legs. 
(c) Third‘pair of legs. Each leg consists 
of many joints —a basal expanded 
“coxa” with a small ‘‘ trochanter” at 
its distal end, a “‘femur,” a ‘‘tibia,” 
a six-jointed tarsus or foot ending ina 
pair of claws (Fig. 175). 
Two cigar-shaped tactile anal cerci, at- 
tached under the edges of the last tergum, 
are possibly relics of the last abdominal 
appendages. 
The ninth sternum of the male bears a 
pair of styles, possibly relics of appendages. 
Both sexes have complex hard structures 
(gonapophyses) beside the genital apertures. 
They are possibly relics of appendages. 
The large black compound | 
eyes. 
The “ upper lip” or labrum, in 
front of the mouth. 
The white oval patches near 
the bases of the antennz, pos- 
sibly sensory. 
In some primitive insects a 
minute pair of appendages, 
known as maxillulz, occurs be- | 
tween the mandibles and the 
first maxille. 
(4) Apair of wing-covers (modi- 
fied wings), rudimentary in 
female of P. orientalis. 
(c)A_ pair of membranous 
wings, sometimes used in 
flight, folded when not in 
use, absent in female of | 
P. orientalis. 
Between the segments of the 
thorax are two pairs of respira- 
tory apertures or stigmata. 
A pair of stigmata occur be- 
tween the edges of the terga and 
sterna in the first eight abdo- |, 
minal segments. 
The anus is terminal, beneath 
the tenth tergum of the abdo- 
men ; a pair of “‘ podical plates” | 
lie beside it. 
The genital aperture is on the 
eighth segment in the female, | 
behind the ninth sternum in the 
male. 
The opening of the sperma- 
theca—the female’s receptacle 
for spermatozoa —lies on the 
ninth sternum of the abdomen. 
