380 GEOGRAPHICAL DISTRIBUTION. 



the general distribution of the family it is found that a 

 greater or lesser number of allied species are confined to 

 special regions, some species restricted to very small areas, 

 and even to special localities. 



Prom the above it will be readily seen that it becomes 

 difficult to draw up any statement of the number of species 

 peculiar to different countries or regions. 



This subject has, however, been fully gone into by Mr. 

 Baker, who, in an elaborate memoir of 47 pages quarto,* 

 shows the general distribution of the order through the 

 different zones and regions, and the relation of the species 

 of the regions to one another ; the data which he has 

 adopted are the localities given in the " Species " and 

 " Synopsis Filicum," the number of species recorded being 

 2228, which are arranged and tabulated in a form showing 

 the regions and countries where each species is found, and 

 the species peculiar to each region. He divides the earth 

 into four zones, namely, Arctic zone, North temperate zone, 

 South temperate zone, and Torrid zone. These are sub- 

 divided into ten regions, of which the following is a sum- 

 mary, showing the total number of species, and also those 

 peculiar to each region. 



AECTIC ZONE. 



1. Arctic zone or region. This region contains 26 



species, none of which are peculiar to it, all being 

 found in the adjoining zone. 



NORTH TEMPERATE ZONE. 

 This zone is divided into three regions, as follows : 



2. Temperate Europe and North Africa. This region 



includes Europe and the whole length of North 



* "Linnsean Transactions," vol. 26, 1867. 



