326 PHYLUM ARTHROPODA. 
GENERAL CHARACTERS 
Like other Arthropods, Insects have segmented Ladies, jointed 
__legs, chitinous armature, and a vertwat-chain of ganglia linked 
to a dorsal brain. Compared with Peripatus and Myrtopods, 
adult insects show concentration of the body segments, decs&éease 
in the number and ucrease in the quality of the appendages, 
and wings tn the great majority. SoS 
Insects are teryestrial and aerial, and xanely aguatie— 
animals ; usually winged as adults, breathing by means of 
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Fic. 172.—-Female cockroach Fic. 173.—Male cockroach 
(P. orientalis). (P. ortentalds), 
trachea, and often with a metamorphosis tm the gourse gf their » 
life history. <> arpeed 43 FEMS 
Th, — ; 
Atiddebdgmen. The head bears a pair of gre-oral antenge, 
and th : endages ; the thorax bears a pair 
of legs on each of its three segments, and, typically, a pair of 
wings on each of the posterior two; theabdomen has no 
appenda dimentary modifications of these be re- 
presented by stings, ovipositors, ett. aaa 
First Type of Insects, Periplaneta (or Blatta).— 
The Cockroacu 
Habits.—The cockroaches in Britain are immigrants 
from the East (P. orientalis), or from America (P. americana). 
