INVERTEBRATE ANIMALS. 
LOS Ves s c) ald We ae a a 
ARTHROPODA. 
Division II, ARTHROPODA or ARTICULATA.—The members of 
the sub-kingdom Aznulosa comprised under this head are gen- 
erally known as Articulate animals, or as Arthropoda (Gr. 
arthros, a joint; and podes, feet). They are all distinguished 
by the possession of jotnted appendages articulated to the body. 
The body is composed of a series of distinct rings or segments 
(technically called ‘‘ somites”) arranged longitudinally one be- 
hind the other (fig. 62). The skin is more or less completely 
hardened by a horny deposit of “ chitine,” with or without lime, 
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Fiz. 62.—Arthropoda, The Sand-hopper, Taditrus Jocusta, enlarged. 
so as to form a resisting shell, to the inner surface of which the 
muscles are attached. There is consequently no necessity for 
any internal skeleton. The nervous system in the young of all 
Articulate animals has its typical form of a chain of ganglia 
placed along the ventral surface of the body, and traversed in 
front by the gullet. In the adult, however, this typical state of 
