226 ANNULATA. 
presence of s¢igyzata and absence of gills ; and (5) the terminal position 
of the genital aperture. 
The antennz are tactile and, like the antennules of the 
lobster, they are also said to possess odfactory 
hairs. The palpi are also tactile. ‘The eyes have 
been already referred to. 
Sensory. 
Fig. 150.—DISSECTION OF COCKROACH FROM THE DorsaL SIpkn. 
(Ad nat. ) 
Salivary Bladder. 
Brain. 
ist Thoracic 
anglion. 
ist Thoracic 
Stigma. 
2nd Thoracic 
1st Abdominal 
Nerve Ganglion. 
Gizzard, 
we , 
Stigmata. { f 
Ventral Abdo- 
minal Muscles. ~q .Hepatic Czca. 
ig as - \ } p Malpighian Tubules. 
Rectum. 
Ovarioles. 
The body-wall is removed and the alimentary canal pulled over to the right. The 
ventral tracheal system is seen as white tubes leading from the stigmata. 
If the terga be gently cut off or freed by a scalpel the 
principal organs of the body are exposed. The mouth 
passes into a duccal cavity provided with a hard 
chitinous tongue. The paired salivary glands, 
with saivary bladder, open by ducts into this part. Thence 
a delicate wsophagus passes gradually into a large and spacious 
crop. At the hind end of the crop is the small thick-walled 
gizzard, provided with six chitinous ¢eeth and strainers, as in 
the lobster. 
Alimentary. 
