DOMAIN OF EVOLUTIONARY HYPOTHESIS 133 



have sought for among our Conifers or Phanerogams, 

 if the solitary surviving species, GinJcgo biloba, had also 

 become extinct and had been buried in some inaccessible 

 place or had not become known to Europeans as still 

 existing ? 



What would have arisen from the Rhyncocephali of 

 the Permian system, or from the Nautiloids and Crinoids 

 if they had been more numerously preserved, we can 

 easily presume from Hatteria (Sphenodon punctata) and 

 the few Nautili and Crinoids which are still living. 

 They would have remained the orders of Rhyncocephali, 

 etc., as in fact is the case with the only Hatteria which 

 represents the entire value of the order 1 (Rhyncocephali) 

 with its widely branched relatives of the past. 



As it occurs to no investigator to regard the present 

 Hatteria as an actual transition from the Newt (which 

 it most resembles) to the Crocodile, just so is no one 

 justified in regarding the Permian Rhyncocephali as 

 phyletic linking forms, as still, however, always happens. 3 



The same remark applies to the Permian Stego- 

 cephali, which for the time being are only known as 

 ' Stegocephali '- i.e. as animals which, like the Amphibia, 

 possessed a free living larval form and two occipital 



1 Hatteria punctata forms in the textbooks the order of the Rhynco- 

 cephali, although to-day it possesses the systematic value of a good species. 

 Ginkgo biloba represents in the botanical system an entire class, although 

 all the still existing individuals are so alike that they only form one 

 systematic species. 



2 R. Hertwig says, for instance, in his textbook, p. 590 : ' In the same 

 way the " Rhyncocephali " lead also to the Hydrosaurians, particularly 

 to the Crocodiles, since a double cheek-bone exists (jochbogen), and the 

 " quadratum " is firmly attached to the skull.' 



