256 MR. G. BENTHAM ON EUPJIORBIACEiE. 



and extreme east of tropical Asia ; but in Mexico and western 

 South America there are two species which, as far as can be 

 judged by male specimens, belong to the same genus. It would 

 seem, therefore, that Jatropha, in its collective sense, was from a 

 very remote period in Africa, in eastern Asia, and in America, 

 spreading and diverging very much in the latter region, less so 

 in Africa, and very little in Asia. 



The vast petaliferous genus Croton must include for our pre- 

 sent purpose its three small offsets Julocroton, Grotonopsis, and 

 Eremocarpus. It is chiefly American, but is also generally spread 

 over the tropical regions of the globe. Out of about 500 species, 

 not quite 100 are recorded from the Old World, where they ex- 

 tend all the way from Africa to Australia and the South- Pacific 

 islands. Of some twenty principal groups into which the genus 

 might be divided, none are peculiar to the Old World, and three only 

 are there represented (Eluteria, Eutropia, and Tiglium), none of 

 them much marked in character. The remaining seventeen are 

 exclusively American, mostly tropical, but with a few offsets beyond 

 the tropics both northward and southward, and many of them 

 much more divergent from the common type than any of the Old- 

 World forms. These divergent forms, however, are aberrations 

 in various directions, not approaches to or connecting-links with 

 other genera. The various sections and subsections hitherto pro- 

 posed are often so very technical and so little in accord w r ith 

 natural affinities that, until they have been thoroughly revised, it 

 would be very unsatisfactory to enter into details as to their 

 geographical distribution. As a whole the genus stands alone. 

 As far as my observation goes, I can point out no other American 

 genus showing any connexion with it, and no near one in the Old 

 World, the least distant being perhaps three small apetalous 

 genera, Cephalocroton in Africa, AdenocJilcena in Asia, and Adriania 

 in Australia. It is not impossible, therefore, that Croton may be 

 of African, or rather of Africano-Australian origin, but spread in 

 very remote times over the general Euphorbiaceous areas, be- 

 coming in subsequent times comparatively little extended or varied 

 in the Old World, but greatly prospering in America into very 

 numerous varied and ever- varying forms, the most divergent m 

 geographical area — the extratropical (northern and southern) 

 being also the most divergent from the parent stock in systematic 

 character. 



Acalypha is generally spread over the tropical regions of the 



