306 PROCEEDINGS OF SECTION C. 



order of appearance and generic affinities with fossil plants of 

 these distant regions, must inevitably lead to error and confusion, 

 as it has done in the past.* 



In further support of these statements I have prepared a com- 

 parative table (PI. XVII.) showing approximately the order of the 

 appearance of characteristic genera of plants in Europe and 

 Tasmania, the latter closely corresponding to the order in 

 Australia. If we examine this table carefully we are compelled 

 to admit the following conclusions : — 



(1) That similarity in the characteristic genera, solely of the 

 rocks of two far distant regions, forms ■primd facie evidence, — 

 not of their correspondence as regards contemporaneity or homo- 

 taxis or parallelism of biological, or stratigraphic progression — 

 but of the reverse of these. 



(2) That such gaps, inversions, and lack of parallelism in the 

 biological progression in separate far distant regions, supports the 

 Darwinian hypothesis of single specific centres of origin ; for if 

 plant life passed through similar stages of development from 

 similar independent specific pairs in every region of the earth, 

 beginning at the same homotaxial stage, we should certainly fail 

 to find such gaps, inversions, and lack of parallelism in biological 

 progression, as those referred to in the table of comparative order 

 of the appearance of plant life in Europe and Australasia. 



The only reasonable conclusions to be drawn from these con- 

 siderations are such as have already been advocated by the author 

 in a paper read before the Royal Society of Tasmania in the year 

 1886,t viz:— 



(1) It is most probable that all the higher specific forms of life, 

 including even those of the known genera of ferns, sprung fi'om 

 one centre and from one pair. 



(2) It is improbable that all species had their origin in one 

 particular hemisphere, but rather : — 



(3) It is probable that some species originated in the Northern 

 Hemisphere, while others had their origin in the Southern. 



(4) It is reasonable to assume where species or genera have 

 spread from the centre of origin, or from a subsequent station to 

 another hemisphere, that a very considerable period of time may 

 have elapsed. 



(5) Where such world-wide destribution of forms has taken 

 place, it is perfectly admissible to conceive that the particular 

 assemblage of organisms in any point or division of a vertical 

 series in either hemisphere, would embrace forms some of which 

 originated locally within the age of the system of formation, 

 while other were immigrants from an opposite hemisphere, dating 

 their original appearance on the globe in a former epoch among 



* See the controversy regarding the age of the Glossopteris-heaxms beds of N.S. Wales, 

 t Papers and I'roc. R. Soc. Tas. 1886, pp. 164-182. 



