328 PHYLUM ARTHROPODA, 
They are omnivorous in their diet, active in their habits, 
hiding during the day and feeding at night. They are 
ancient insects, for related forms occurred in Silurian ages ; 
they are average types, neither very simple nor very highly 
specialised. Their position is among the Orthoptera, in the 
same order as locusts and grasshoppers. The hatched young 
are like miniatures of the adults, except that wings are 
absent. If there are wings, they appear at the last moult, 
when the cockroach becomes sexually mature. 
Fic. 174.—Ventral aspect of male cockroach with the wings extended. 
An imaginary median line has been inserted. 
A., antenne; £., eye; P.7., prothorax; W1, first pair of wings ; 
W*, second pair of wings; C., cercus; St., style; Co., coxa; 
Tr., trochanter; #., femur; 772., tibia; 7a., tarsus. 
Skin.—There is an external chitinous cuticle and a 
subjacent cellular Jayer—the epidermis or hypodermis— 
from which the cuticle is formed. The newly hatched 
cockroaches are white, the adults are dark brown. 
Moulting, which involves a casting of the cuticle, of the 
internal lining of the trachez, etc., occurs some seven times 
before the cockroach attains in its fifth year to maturity. 
The muscles which move the appendages, and produce 
