76 INSECTS AND 
uted to disci zoological element, or ring of the body ; no 
single part of the body is much handtak above the rest, so 
as to subordinate and hold the other parts in subservience 
to its peculiar and higher ends in the animal economy. 
But when we rise in the scale of articulate life, we see 
at once the action of a new principle. First in the Crus- 
tacean appears a broad distinction between the front and 
_ posterior end of the body. The rings are now grouped 
e Tes > into two regions, and the 
i J hinder division is subor- 
dinate in its structure and 
' uses to the forward por- 
tion of the body. Hence 
the nervous power is 
transferred in some de- 
paistia endai tite: A tery, SPP! towards the head. 
a. cephalothorax; b. abdomen, The organs performingthe 
functions that distinguish animals from plants, such as 
locomotion and sensation, all reside in the front region; 
while the vegetative functions, or those concerned in the 
reproduction and nourishment of the animal produced, 
are mostly carried on in the hinder region of the booi 
(the abdomen). 
The Crustacean cannot be said to kavo a true head, in 
distinction from a thorax bearing the organs of locomo- 
tion, but rather a group of rings, to which are appended 
the organs of sensation and locomotion. 
s oe jaws become Temarkably like claws; or 
