266 ME. G. BEHTHAM OX EUPHORBIACK^. 



species, into the connexions and geography of which it would be 

 premature to enter until the rich collections, now in the Paris 

 Herbarium, shall have been fully worked up. Some appear to 

 be quite isolated, others more or less connected with the Malayan 



flora. 



I pass over also for the present six Madagascar genera com- 

 prising 7 species, which I have not had the opportunity of seeing. 

 Many Madagascar plants have been described from single speci- 

 mens, sometimes imperfect, in the herbaria of the Paris Museum 

 or of Dupetit Thouars ; and the Kew Herbarium is compara- 

 tively deficient in the flora of this island, one of the most interest- 

 ing in respect of botanical geography. For that reason it is 

 impossible now to enter satisfactorily into the questions con- 

 nected with the close affinity of various genera or species endemic 

 in Madagascar and in the Mexcano-Cuban regions respectively. 



In conclusion, omitting the Eucrotoneae, the Hippomaneae, and 

 the genera clustered round Phyllanthus , it will be observed that 

 we have in America 14 monotypic genera, of which only one 

 or perhaps two show any affinity to other American genera ; 

 whilst in the Old "World, among the 35 montoypic genera 

 at least 20 may be approximated to one, two, or more Old- World 

 genera. 



Among the smaller, but not monotypic, American genera there 

 are only three, or perhaps four, cases where two or three can be 

 brought together as being rather more nearly allied to each other 

 than to any others. In the Old World at least a dozen such 

 groups of two to six allied small genera might be formed. 



Taking the largest genera in each continent, in America 

 Manihot and Argitharnnia are quite isolated. In the Old- World 

 MaTlotus and Macaranga pass into each other ; and these, as well 

 as Antidesma and Claoxylon, are each surrounded by a number 

 of small allies often connecting them with other more distant 

 ones. 



All these considerations, as well as those I have brought forward 

 in treating of genera common to the two continents, appear to me 

 to favour the hypothesis above announced, that the most ancient 

 home of the order was in the Old World, whence it spread 

 in very remote times to America. And if we imagine that chief 

 ancient home to have been somewhere in the supposed tract ex- 

 tending from tropical Africa and Madagascar to Australia and 

 the Pacific, there are indications that in the Old World there 



