CONTENTS. 



Pakt I. 



PAGE 



External form, habits, geographical distribution and 

 classification ....... 1 



Part II. 



External skeleton (skin and hair), and internal skeleton 

 {the bones") ......... 84 



Part III. 

 Nervous system, visceral anatomy, summary of 

 characters and question of affinity and origin . . 134 



d>y//f/ 



