Lnns'EAif SOCIETY or LOJfDOJf. 27 



known, easily observed species. It would not be a bopelessly 

 large task, for instance, by a combination of local botanists, to 

 get a very complete map of the distribution of such a plant 

 as Chlora perfoliata, showing the soil, the elevation above sea, 

 the aspect, the rainfall, and even the local abundance. We 

 might, further, record the insect, if any, which fertilizes the 

 species, and its local abundance. It might be possible to make 

 a similar map for several years in succession. It appears to 

 me that there is greater hope of result from such records than 

 from a comparative tabulation of County Ploras, each containing 

 700 to 1000 species. 



The first attempts to discover the affinity of the Macaronesian 

 Plora were grounded on tabulation of all the species in Webb 

 and Berthelot's work ; and the inference was that the Flora of 

 the Canaries was more closely allied to that of Spain than to 

 that of the Atlas and the adjacent coast of Africa. Later 

 writers, excluding the weeds of cultivation which have been 

 brought from Spain for 400 years, and narrowing their attention 

 to woods and ravines apparently unaffected by man, have arrived 

 at very different conclusions. But in these islands there must 

 always remain an option, regarding a large number of plants, 

 whether they are "truly indigenous" or not. We have a diffi- 

 culty on each side of us : on the one hand, in England or 

 Germany, where we have a large number of competent observers 

 who can tabulate the present distribution of the oak, ash, &c., 

 the aspect of the country is artificial by reason of planting and 

 grubbing. On the other hand, in the forest primaeval, the one 

 or twu' competent observers can only record their general im- 

 pressions: they cannot map the numerical distribution of species 

 over several hundreds of square miles. Some of the work of the 

 Indian Forest Department, in mapping fully the distribution of 

 one tree of economic value, might be utilized ; and the close 

 observations of Kurz and Prain on the Flora of some small 

 islands where the forest is untouched by man, and the narrow 

 belt of immigrant vegetation can be accurately traced, are of the 

 greatest interest. 



In the table I have proceeded, as tabulators must, by the 

 comparison of identical forms. But geographic relation can 

 sometimes be more surely established from the consideration 

 of non-identical species. We heard Mr. Scott Elliot in this 

 room commenting on the remarkable fact that a percentage of 

 the plants of Senegambia is common to Guiana. Mr. Elliot 

 attributed this to the great traffic between AYest Africa and the 

 West Indies. Now, some of the species common to Senegambia 

 and Tropical South America are very remarkable plants : such 

 are, among the sedges, Scirpus spadiceus, Boeck., and Ascolepis 

 hrasiliensis, Benth. ; there can be no question of the identity of 

 these in the Old and New World ; they are well marked species ; 

 they are not weeds of cultivation, and not likely to have been 

 carried by ships. Still, they may have been so transported ; 



