Chapter V 



-65— 



Types of Areas 



The diverse types of vicarious areas were subjected to a critical and 

 detailed analysis by Vierhapper (191 9), and we shall summarize this 

 analysis here. 



The chief type of vicarism may be called spatial vicarism, and, de- 

 pending on whether the vicarious species are distributed horizontally 

 or vertically, we may distinguish between horizontal and vertical vi- 

 carism. The first is of more common occurrence than the second, since 

 the latter naturally may be found only in mountainous regions. Spatial 

 vicarism may occur in different regions isolated from or mutually 



Fig. 7. — Vicarious species of pine, Pintts Strobus and P. 

 TKoniJco/a, in North America. (After Victorin : " montrant la differenci- 

 ation morphologique due a I'isolement geographique. L'isolement est 

 ici le resultat de I'extension, a la fin du Cretace, d'une mer interieure qui 

 separe I'Amerique du Nord, dans le sens de la longueur, en deux massifs 

 continentaux. A-A', C6nes; B-B', Section des feuilles; C-C, Pointes 

 des feuilles; D-D', ficailles et graines."). 



exclusive of one another — regional vicarism. In other cases vicarious 

 species may be found within one and the same region but under 

 different habitat conditions — intraregional vicarism. Such conditions 

 include different kinds of soil substrata, e.g., volcanic rock and lime- 

 stone, solonchak and podzol soils, sandy and hardpan soils, shady and 

 sunny habitats, etc. Among vicarious forms of this type there should 

 be mentioned the many so-called colored species or races, the color of 

 whose flowers changes depending on local habitat conditions. 



Contrasted to this spatial vicarism is vicarism linked with the time 



