362 NERVOUS SYSTEM OF VERTEBRATA, Yes 
united into one continuous mass ; and this mass, constitut ng 
‘the Brain and Spinal Cord, is inclosed within the bom, 
Fig. 190.—Nzrvous System or Ocropus (Povutp). 
‘casing formed by the skull and vertebral column, in al a 
‘manner as to be protected by it from injuries to which it 
“would otherwise be continually liable ($$ 72, 73). We h 
seen that among the Invertebrated classes the nervous sys 
has no such peculiar defence, but lies among the other organs 
‘sharing with them the protection afforded by the general ha 
‘envelope of the body. But in the Vertebrata, its developmellt 
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