AND THE APE THEORY. 33 



the skull theory which now started into prominence 

 was this : " How, historically, has the skull of man and 

 of the higher animals originated from that of the lower 

 animals ? How is the development of the bones of 

 the skull from the vertebrae to be proved ? " The 

 answer to these difficult questions was supplied by the 

 first comparative anatomist of the present day, by Carl 

 Gegenbaur. After Huxley had pointed out that the 

 ontogenesis or individual development of the skull by 

 no means favoured the older hypothesis of Goethe and 

 Oken, Gegenbaur brought forward evidence that the 

 fundamental idea of that theory was correct ; that the 

 skull does in fact correspond to a series of coalescent 

 vertebrae, but that the separate bones of the skull are not 

 to be regarded as representing parts of such modified 

 vertebrae. The skull-bones of all recent vertebrate ani- 

 mals are rather, for the most part, dermal bones, which 

 have come into closer connection as supplementary to 

 the cartilaginous primitive skull. We can even now 

 trace the number and position of the original vertebras, 

 from which this primitive skull originated, by the 

 number of the vertebral arches (gill -arches) which are 

 attached to it, as well as by the number and position 

 of those vertebrae, from nine to ten. Of all the recent 

 vertebrata, the cartilaginous fishes, or Selachians, have 

 most nearly preserved the form and structure of this 

 primordial skull. These Selachians, the Eays and 



