284 



APPENDIX. 



head of the mammals vary greatly, it is always composed of the 

 same parts, marked by the same processes and united in the samt; 



FIG. 481. 



Ape. 



Bat. 



Mole. 

 Dog. 



Seal. 



Deer. 



Whale. 



Bird. 



Tortoise. 



Fish. 



order. Any difference is only a modification of form and structure, 

 rather than of omission or addition. These variations are least 

 observable in the embryonic state, and become more apparent in 





