3 20 Jourjial of Travel and Natural History 



applied on the same principle to all, and do not disturb the general 

 proportion. 



Dr Kuhn, on the contrary, has made up his lists from all kinds 

 of sources ; collections examined, and lists made up by himself; 

 catalogues published by some authors, monographs and Floras by 

 others, and isolated notices and descriptions of species; and with the 

 infoniiation drawn from these heterogeneous sources, modified and 

 corrected according to his own estimate of what was likely, or what 

 had been suggested by others. 



It may, however, be worth while for the use of others, to point 

 out one or two objections which occur to us, to the mode in which 

 he has tabulated his statistics. The plan he has adopted is to 

 tabulate the species according to the continents of our modern 

 maps ; not into regions whose limits have been determined by 

 the affinity of their productions. The continent of Europe, for 

 example, is not the same Europe as that of the student of 

 geographical distribution ; in his Europe the north of Africa is 

 included. Neither does the continent of Asia of our maps corre- 

 spond with his continent of Asia. His continent goes no further 

 south than the Himmalayan range — all south of that comes into 

 another region — the Indo-Malayan, and so on. Dr. Kuhn (the 

 subject of the body of his book being African ferns) naturally 

 gives a table of the numbers of African species found else- 

 where — viz., in Asia, in Europe, in America, &c. But, when he 

 simply records a species as found in Asia of the maps, he leaves the 

 student of geographical distribution in the dark on the most impor- 

 tant point — whether it is found north of the Himmalayan range or 

 south of it. The inferences to be deduced from its occurrence in 

 the one being widely different from those from its occurrence in the 

 other. If its Asian habitat means Kamschatka, we should infer 

 that the species was of veiy antient origin, and that its range 

 once probably extended all over the world, for everything is 

 against any recent union or continuity of Africa and Kamschatka. 

 Whereas, if its Asian habitat meant India or Java, it would suggest 

 its common occurrence there and in Africa as the result of a former 

 continuity of these regions, there being other grounds for beUeving 

 this to have been the case. 



The body of the essay consists of a list of the ferns, with 

 descriptions of the new ones collected by Kersten and Linck, 

 the botanists who accompanied Baron Van Der Decken in his 

 disastrous expedition into the interior of Eastern Africa ; and 



