354 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



Ungulates, table of Chasmo- 

 therium and Lophiodon 

 Branches, 201 



. teeth of, 225 



transformation of tridactyl 

 hoof to monodactyl form, 

 105 



transition between Eden- 

 tata and, 153 



Unio, 68, 127, 271 



asiierianus, 128 



bigorrinensis , 128 



circulus, 128 



moulinsianus, 128 



Pacomei, 128 



rhomboideus, 128 



spharicus, 128 

 Urchins, 49, 67 



early forms, 256 



origin of the family of the 

 Cidaridae, 233 



Cidaris unchanged from Per- 

 mian times, 163 



Ursavus, miniature bear of 



Miocene times, 106 

 Ursidse (bear's) teeth, 103 



VALLETTA, 216 



Varieties, de Vries' experi- 

 ments on abnormal, 274-5 



Variation (individual) causes 

 still unknown, 77 



Variations (sudden), Saint - 

 Hilaire's hypothesis, 33 



Vermiceras, 260 



Vertebrates, Acranian, 51 



and Invertebrates, 193 



Cope on, 78, 219 



Darwin on origin of, 41 



derived from Annelids 

 (Semper's view), 86 



Vertebrates, derived from Asci- 

 dians (Kowalevsky), 50, 86 



derived from classes of 

 Fishes, 83 



development of, 263 



earliest appearance, 245,252 



Embryos, 254 



evolution of, 219, 239 



Haeckel on origin of, 50 



Lamarck on origin of, 31-2 



migrations of, 281, 293 



origin of, unknown, 86 



Palaeontological history, 247 



persistent embryonic types, 



255 



phyletic branches, long - 

 evity of, 171 



rapid and slow evolution 

 amongst, 167 



teeth, 225-7 

 Virgatites, 285 

 Vivipara Hornesi, 165 



Stun, 165 

 Volborthella, 246, 326 



WALRUS, resemblance of limbs 

 to those of some Triassic 

 reptiles, 224 



XIPHODON, 7 



" YOUTHFUL " characteristic of 

 Ganoid fishes, 241 



stages, traces of in certain 

 Molluscs, 257, 262 



ZANCLODONTID^;, 300 



Zebra, 73 



Zoophytes, Haeckel on, 46 



