260 MB. G. BKNTMAM ON EUPIIORBIACE^. 



and perhaps a Brazilian, not yet very perfectly known species which 

 seem to be as near to Exccecaria as to Sebastiania. Maprounea has 

 2 tropical American and 1 tropical African species. Stillingia has 

 11 American species, 1 in Madagascar, and 1 in the South-Pacific 

 islands. The American ones are not limited to the tropics, ex- 

 tending northward into the United States and southward to the 

 Argentine States ; and the closely allied Adenopeltis, 1 species, and 

 Colliguaia, 5 species, are all extratropical South-American. Of 

 the remaining genera of typical Hippomanese, two only are peculiar 

 to the Old- World, Somalanihus and Pimelodendron, containing 

 between them about 10 species; and seven w r ith about 50 species 

 are tropical American, viz. : — Senefeldera, 4 species, and Actinoste- 

 wion, 24 species, from South America, chiefly Brazil ; Hippomane, 1 

 maritime species from the West Indies and neighbouring coasts ; 

 Ditta, 1 species, Bonanza 6 species, and GymnantJies, 10 species, 

 all from the West Indies, but one or two of Gymnanthes extending 

 into South America ; and Dalembertia, 4 Mexican species. These 

 Hippomanese have thus less of the African or Mascarene character 

 about them than any other one of the widely spread groups ; their 

 early differentiation must have taken place chiefly in America and, 

 to a less extent, in the eastern rather than in the western 

 portion of the great Africano- Australian region. The three very 

 distinct genera placed at the end of Hippomaneae — Hura, 2 or 3 

 species, Algernonia, 4i species, and Pera, about 20 species — are all 

 tropical American. 



Four American genera or marked sections, Amanoa, Caperonia, 

 Eimlchornea, and Maprounea, all abundant chiefly in east tro- 

 pical America, are represented each by one distinct species in 

 west tropical Africa, which suggests the idea that the latter may in 

 ancient times have been in some manner derived from America, 

 rather than that they are remains of a parent type dating from 

 before the disruption of the ancient communication. 



There are very few species of EuphorbiaceaB common to the tro- 

 pical regions of the two great continents ; and these are in some 

 cases so generally diffused, that it is difficult to say which was 

 their original country, or how ancient must have been their dis- 

 persion. These are : — 



(1) Weeds of cultivation : Euphorbia pilulifera y E. thymifolia 

 (E. serpens?), Phyllanthus Niruri, and Croton lobatus. 



(2) Herbaceous twiners of ready dispersion : Tragia volubilis 

 and Dalechampia scandens. 



