COCKROACH. 
329 
the abdominal movements essential to respiration, are 
markedly cross striped. They 
are in many cases attached 
to special tendons, which 
arise as cuticular invagina- 
tions, and are lost and re- 
placed at each moult. 
Nervous system.—A pair 
of supra-cesophageal or cere- 
bral ganglia lie united in the 
head. As a brain they receive 
impressions by antennary and 
optic nerves. By means of a 
paired commissure surround- 
ing the gullet, they are con- 
nected with a double ventral 
Fic. 175.—Leg of cockroach. 
¢., Broad expanded coxa; ¢~, troch- 
anter; f, femur; ¢z., tibia; ¢a., six- 
jointed tarsus with terminal claws 
and adhesive cushions. 
chain of ten ganglia. Of these, the first or sub-cesopha- 
geal pair are large, and give off nerves to the mouth-parts, 
Fic. 176.—Moutn appendages of cock- 
roach.—After Dufour, 
I, Aln., mandibles ; II. first maxilla ; C., cardo ; 
Sz, stipes; Z., lacinia; G., galea; mx p., 
maxillary palp; III. second maxille or la- 
bium; S7., submentum; #., mentum; Z., 
lacinize ; Bo paraglossa 3 2, poy labial palp. 
etc. ; from each of the 
ganglia of the thorax 
and the abdomen 
nerves are given off 
to adjacent parts. 
There are three pairs 
of ganglia in the 
thorax, and six in the 
abdomen, of which the 
last is the largest. 
From the cesophageal 
commissures visceral 
nerves are given off to 
the gullet, crop, and 
gizzard. Besides the 
large compound eyes, 
there are other sensory 
structures —some of 
the setee on the skin, 
the maxilla (to some 
extent organs of oo 
the antennse (tactile and olfactory), the anal cerci (tactile 
and possibly the oval white patches on the head. 
